What makes you think the franchise would be so much better if Interplay still owned the IP? Do you think Tactics and BoS were better additions to the franchise?
Seriously there is a reason they had to fund PoE through kick starter, i love that game but old school RPG's is a niché genre, and not something publishers are interested in. There is absolutely no guarentee it would have been better,
The only thing that's safe to say is that it wouldn't have been open world,it would have a bigger focus on story and there would probably be more bugs. And not every Obsidian story is all that good, ever played NWN2?(Not Mask of the Betrayer, that was fantastic, the OC)
You can dream up what they shoulda,coulda,woulda done till your face turns blue, reality would never match it anyway. Bethesda has the IP now and they're putting their spin on it, just enjoy it for what it is or don't.