OK, the here is my 1c worth.
1. Constructors have the following usages (maybe more, just haven't thought of them). 1) buld a starbase 2) build research 3) build econ 4) build modest defenses (say against early pirates perhaps) 5) build culture 6) build heavy defenses (strong points) 7) create a forward base for attack (allowing more modest range modules on ships) 8) mine resources 9) obtain relics 10) provide early warning posts (perhaps with extra scanning modules). So the constructor/starbase system is flexible and combines with many different critical uses often in the same game. Ex. do you want a string of starbases or a line of ships to guard a flank while attacking in another direction. You can build constructors or ships. Ships are mobile, but starbases give you many additional later options. Ships are expensive to upgrade. I find it hard to say that the micro involved in designing and placing ships is less intensive than placing a starbase and hitting "request constructor" a few times. But my point is that I want that flexibility to decide how to use stuff and where to place it even after I build it.
Most of the defenses I build on starbases result from having the 2 constructors for 1 pragmatic choice and having no immediate use for the second one. So I put in some defenses, can't hurt. LoL.
2. The comment has been made repeatedly that this is all about the late game. Ok, currently I am on turn 248, gigantic universe, playing a custom race (the Fones) as pragamatic against all the standard races and "common" minors. I currently have 110 starbases, 275 ships, and 59 colonies. Other than the Drengin and one of the minors everyone is still in the game, and I am about to start what will turn out to be a two front war. (I am sure the Yor will join in with the Krynn, lol). At this point I am placing about 5% of my time on constructors (mainly to have a few ready if I need outposts during attack) about 15% of my time on colony maintenance, and the rest on ship design, build choice, and placement. There was a point early in the game in which I did build quite a few constructors to get my research and manufacturing planets going, but I had few colonies then so it wasn't an issue.
Side Note: The Yor are malevolent and yet I still can't attack them. Not sure why. Must have missed something. Nothing in the malevolent table or the UP seems to provide that.
3. I specialize just about every planet I need, and I generally spend almost nothing on starbase defense. I use my fleets for that. Perhaps when pirates get meaner I will have to change that or be dedicating my fleet to anti-piracy. So I generally only use 3 or 4 constructors per base and usually during the late early stages of the game. Factories or labs or rarely culture stuff; or relics (highest priority of course). But I purposely am going for a play style that limits constructor builds because I generally need colony ships (early) and combat ships (later) more urgently. Simple question: if you are spamming a huge number of constructors why aren't you instead building a fleet to destroy your evil neighbor, or defend against him. To each their own, I suppose.
4. That all said I am all for helping manage things. I saw a mention earlier that there needed to be a way to cycle through shipyards to check on stuff. My suggestion is to be able to cycle through starbases so that you know whether to click "request constructor" or not. Can you upgrade the lab on the starbase? Click, done.
I admit that early on I don't carefully figure out how many constructors I need and etc. I sense the situation in the game, how many colonies need built up, and just click constructor a few times on certain shipyards. I may set a rally point for those stabases so that the constructors head to the right area. Then I send them when I get them (if I need to), it isn't a big deal. Exact placement to get the maximum? Well, I take the low lying fruit. I try to mine 2-3 rocks at a time. I try to support 2 or even 3 colonies at a time, and so forth, but I don't make a careful study of it. Perhaps when the AI gets a lot better I will have to and my opinion may change.
5. My last point is that the game is still changing quickly. Their will be a big change in the AI coming up, and pirates will get their own bases. This will force changes in how one prioritizes things like constructors vs combat vs planet builds. How that will impact things I don't know, but I am thinking I will be building fewer starbases early on because I will need ships.
In summary ideas to streamline the game are fine. Ideas that require major reorganizations of the code aren't likely to have much appeal though. I have suggested a couple of simpler things. Personally I am not that concerned with constructor spam. I do admit that if I were playing on insane with only 6-8 opponents the building phase of the game would take forever and it would mean 1,000 starbases. But that isn't much of a game to me. I prefer a game where each faction has a fair shot at a reasonable start but that contact wont take 200 turns. So on insane I would think 30-50 or more factions about right (haven't tried though). I would be much more interested in some system that lets me know I can now build X (usually a capital building of some sort) on colony Y (that I have prepared for it), but even in that case as the tech tree gets set and I get more familiar with it I will know what to do. (Guess what, I use auto upgrade universally at the moment.)
Well, that's my take. At the moment I am organizing my fleets. Hopefully the colonies are managing themselves ok. If some colony needs a build, they can send a memo.