I don't think people need to keep suggesting ways to nerf ranged combat, my understanding is that it is already pretty weak. Being able to take more turns just scales really well with all offensive abilities. For example if one had to choose between doubling damage and doubling the number of turns one can take, turns is always better, because it results in the same total damage and gives more movement. Further it allows dividing damage over more units which is good if the enemy has low health relative to the strength of your attacks. There are other benefits as well, but taking a lot of turns is really good. This is why kiting is possible, but it also allows other bad things like alpha striking an opposing army before they can even act and disable locking.
But the same things that make taking lots of turns really strong also make it really weak. Consider two units, unit A does 10 damage and unit B does 5 damage but attacks twice as often as A. Both do 10 damage in a round. However if we have a spell that lowers the damage per attack each does by 1 A now does 9 in a round while B does 8. Just like linear (as opposed to percentage based) buffs are better placed on units with high numbers of turns linear debuffs hurt them more especially if they sacrificed other stats to get high initiative. Periodic healing or beneficial effects are also really good on high initiative units, similarly periodic damage effects could really punish high initiative units if they occur every turn because high initiative units take more turns (of course this isn't really true if the effect just lasts for a certain number of turns, it will deal it's damage quicker, but have the same total effect regardless of how often a unit takes turns). Along the same lines because units with high initiative attack a lot could we have skills that punish attacking? Attacking a fire elemental carries a chance to take fire damage? A unit whose defense increases the more often it takes damage?
Finally I have a question (since I am not in the beta) which is what is the opportunity cost of getting high initiative? If I went for melee damage instead would my damage output be comparable? I think this problem would probably be solved by just making initiative grow more slowly for heroes, or faster for non-heroes so it scales more comparable to other ways of increasing effectiveness. As others have suggested this could be done by making the base initiative 100 or just giving out less of it.
Another option is to implement implement a sort of round system, where a round is the number of turns it takes for each unit to move at least once and then set a maximum number of turns a unit can take in a round. If you have crazy initiative you might get two turns right at the start of the round, but then have to wait until the slowest unit goes to take another turn.
tl:dr IMO Initiative is the cause of kiting and other imbalances. Punish lots of turns with debuffs and periodic damage effects or just make it scale better.