Coko, increasing the string limit is one of the easiest things I can imagine they'd be able to do. Come on, how gawdamn hard is it to do dynamic memory, Blizzard? Seriously.
Some things I think they should address:
- No string limit.
- No unit limit.
- No 'Create unit with properties' limit.
- Adjustable supply limit.
- Adjustable unit HP (add and subtract, etc., and none of that percentage nonsense).
- Trigger and regular staredit-placable Xtra units.
- No limit on terrain edges (those who've hit that error know what I mean).
- Dark swarms belonging to the player who cast them. (

)
- Unlimited switches (they're a fricken bit each)
- Extended "Orders" list (like in addition to 'Attack', 'Move', and 'Patrol', they also had 'Stop', 'Hold', 'Mine', 'Spell 1', 'Spell 2', etc.)
- No. God. Damn. Wait. Blockers!!!!!!1
And some things unlikely but desirable that they could address:
- Adjustable unit speeds/acceleration.
- Extended map size limit.
- Better. flipping. pathfinding. ai.
- Editable replays (cool for making movies, complete with sounds, center view, transmissions, etc.)
I doubt they'd have to spend more than a weekend to do the programming for that, if they know how. Most likely the politics are what's stopping them, such as having to run it through "quality assurance" and having everyone run a new patch, etc.