For the regen arguments, regeneration was only broken because it occured on the units turn, making very high initiative units heal for insane ammounts. Changing regeneration to a fixed timer irrespective of the units combat actions would make the effect much less broken, and considering that setting a limit on combat turns available would require making a fixed timer anyway I don't see why it couldn't be implimented this way. That said, if regeneration no longer works in combat, it's effect on the strategic map needs to be much more powerful than it is currently. Healing the unit to full (or practically to full) after each turn would make this enchantment worthy of the mana cost per turn.
For the combat turn limit arguments, a reduced number of turns actually encourages different tactical behavior and adds more strategic depth with the possibility of reinforcements. Turn limits should be imposed that directly impact the ability to defeat units however, rather than just designed to prevent kiting over long periods of time. That is to say 20 turns is long enough to prevent excessive kiting, but doesn't provide any opportunities to reinforce a group against a reasonably sized army. If turns were limited to say 6 or 7 then defeating defenders might take several attacks, and rushing your soldiers in to suicide to take that city before reinforcements come would be a viable tactic as would simply having all your defenders use the 'pass' turn option to increase defense while waiting for backup from another location.
However... armies can attack multiple times per turn, and this would place an unbalanced priority on strategic move speed. A fix of this nature would likely require a limit of 1 attack per turn per army (that does not consume movement and the unit can still move afterwards) and would require units to form armies on tiles they pass through and are not simply told to enter, to prevent multiple units in seperate armies from blocking enemy advancement.
There is a secondary issue that might be overlooked however, and that is completing quests that force the player through multiple tactical stages. The arena quest and several dungeons would be impacted through a turn limit timer and if the only reason for a turn limit is to prevent kiting, this could very easily be resolved by requiring the unit to expend movement points (or remain stationary) to fire.