RTWP is not the problem.
D&D 2nd Ed. was.
Melee characters did lack tactical depth, with almost no other choice than hacking until the sword connects with the target (it changed a bit with high levels and ToB)
And there was not Attack of opportunity either.
There wasn't much positionnal gameplay (except for backstabbing may be)

I mean , take a look at Pathfinder : it is RTWP, and much more interresting that Baldur ever was (gameplay wise)