I actually used the WC3 Mapmaker. Last hittingwasa limitation of the engine. You could maybe write complicated trigger to get around it (I tried doing this) but I assume it was a healthy part of the game before that was even considered.
Well that's the thing, you can rework everything via triggers, that's why technically the WC3 "engine" has very few limitations. You can easily make the bounty for last hits 0 though, and then add constant gold, or remove gold entirely, and I doubt making xp global would be that hard since there's already global xp stuff in dota(when you last hit a hero with a global skill you gain xp and it's shared with everyone that's actually in range, so there's a precedent).
Last hitting is a layer of complexity that acts as a filler when nothing else is happening. If you play a jungler(autoattack jungler not minion jungler), you see what happens when you remove last hitting, you just stand there doing very little to nothing while looking at the map to figure out what you should be doing next cause there's nothing else to do. This is what happens when you remove last hitting in lanes. You'll be standing there looking for something to do.
You could think that'll encourage more fighting, but as I touched on shortly in my last post, that's only assuming it is actually possible to kill people in lane early on, which I'm less than positive about. It would either require long CC(haha yeah nope), displacement skills(like the pudge hook, but it seems to be the only one they've shown) or for towers to be fairly weak which doesn't make much sense. So most likely, you won't be doing much of anything if you're not retarded until the secondary objectives open, and then everyone will go for them because who the fuck wants to stay in lane doing nothing. Which is similar to the wow AB issue(to take a blizzard problem), where you wanted to have one guy staying on defense at the farm/whatever the other one was, but most pubs would just leave it undefended cause it sucked staying there vs rushing to the blacksmith/mill/mine. It's an anti pub friendly mechanic, which is questionnable design for a casual oriented game. No one wants to stay in lane to leech xp for the team if there's nothing to do there.
At least in dota/lol, you can focus on your last hitting, increasing your own wealth by a good amount and feel good about it, instead of being like "oh well everyone's at dragon/roshan, I'm gonna go there too fuck this empty lane".
Even assuming the removal of last hits is a good thing though, I don't know why the removal of items is. You could get gold by completing team objectives and still have that layer of customization.
Not saying it's not going to be fun to play or sucessful though. Just discussing mechanics and how they'll impact the game.