You don't have to completely avoid upgrading your starbase, just lean towards defense modules sufficiently that your fleet still has a higher result from the formula (total attack / [total defense + HP]).

But what's the point of wasting the money if you're going to have a fleet there defending it?

I agree you should be able to fleet starbases and ships (and the AI should). Starbases are so important, particularly mining resources, that the attacker should have to really work and lose a lot of material to take an upgraded starbase down. At the moment, low hit points and the fact they only get one shot per round (even if it is super powerful) makes them extremely soft targets.

Why do star bases need to have a logistics value? Logistics imply coordination/movement, but a starbase is just going to sit there and its everyone else that needs to be coordinated around it.

I don't really see a down side to putting star bases in fleets (with regards to game breaking exploits), you can't assault a planet with it or attack shipping lanes or anything else, you just open up the possibility of using the starbase defensively as they would appear to be intended.

IE a string of "forts" around your empire that you can fall back to if things get rough. You can have damaged front line ships limp back for some cover to repair etc. or have lone transports hop from base to base for cover on their way to the front lines.

It would definitely make it more of a challenge to assault one rather than just send an extra small fighter to blow it up.

Why do star bases need to have a logistics value? Logistics imply coordination/movement, but a starbase is just going to sit there and its everyone else that needs to be coordinated around it.

Movement, in a logistical sense, is important for Starships, for Starbases however, not moving does not mean they should not be subject to a logistical point value. As stated in an earlier post, these constructs are massive is size and logistics deals with other aspects as well, not just movement.

Logistics : the branch of military science and operations dealing with the procurement, supply, and maintenance of equipment, with the movement, evacuation, and hospitalization of personnel, with the provision of facilities and services, and with related matters.

They have already a logistic value of 6...

Granted they do, but I do not believe the intent was for the logistical value of a fleet but rather for your overall logistical value and how many starbases you may build before you have to start paying to have them constructed.

I am still fairly new to the game and do not know all the ins and outs, so as far as logistical point values and sorts I am only going on what I have experienced thus far.

You actualy fight battles together with your base(s) if you place your fleet on the same tile. No need to form a fleet: If there are logistic points left the starbase will be in the same battle with your fleet- just check the battleview options to always see the battles and you will see... all installed starbase modules will be in battle alongside...

By the way - The dictionary definition of logistics is: "The time related positioning of resources." However your starbases don't really supply, market or transport any resources (to your fleet), but what they do is to add to your empire's economy and/or industry

ps. actualy I never saw any use in Military bases, since Economic and Mining bases are already heavily fortified and armored...

I agree about the storage capacity of a Starbase but, there are several different types of bases out there. You would have a storage or resupply depot, but eventually they would have to be re-supplied themselves. You would also have your military, research and development, mining and exploration platforms, as well as your deep space observations posts. Not to mention Starbases that would cater just to vacationing civilians. All these bases would need resupply and may even be the ones suppling.

However your Starbases don't really supply, market or transport any resources (to your fleet), but what they do is to add to your empire's economy and/or industry

I look at it somewhat differently, to an extent I guess. The Military Resource is mined via the Starbase. This is a direct correlation to the Starships Weapons and Defenses as outlined in the resources definition.

" These resources contain a special type of energy that magnify your weapons and shielding on your ships which makes them stronger and more powerful. All your weapons and shields gets a +X% bonus after the next turn. "

https://www.galciv.wikia.com/wiki/Resource

I think all things relate to each other in one form or another, the planet helps Starbases and fleets, as well as Starbases helping fleets and planets and even fleets helping Starbases and planets. With all 3 at your disposal, and used the way they were intended, you can do great things.

Just my thoughts.

You actualy fight battles together with your base(s) if you place your fleet on the same tile. No need to form a fleet: If there are logistic points left the starbase will be in the same battle with your fleet- just check the battleview options to always see the battles and you will see... all installed starbase modules will be in battle alongside...

Are you talking about military bases or about econ/influence/mining as well?

milbase bonuses are in the whole AoE, but I've never noticed any other base get added into a fleet battle (especially as if I've loaded up the base with weapons/armor, it is likely "stronger" than the fleet for picking purposes).

It would be nice (and realistic), but I think this isn't done for balance reasons. Being able to deliver an uber-powerful attack all over a sector is probably just too powerful to allow. Especially once you consider how many cheap constructors you can get for the cost of a fleet that could do the equivalent amount of damage.