I am completely for it. It worked in Dota - that much is proven. People still bluffed in Dota, it just wasn't done in the same matter as Demigod (why is he leading me towards the woods when I could kill him there? Is there an ambush? I don't see all the heroes on the minimap, oh crap!)
Regardless I don't see it as hurting Demigod, only helping it. What would you do differently RIGHT NOW if you could suddenly see you opponent's inventory. For most aspects of the game not much. For the interaction with enemy heroes that may change - in the beginning you would be super cautious - oh no, he's got a potion! I can't kill him now, he'll just run and use it and I'll die. I better not even attack him at all.
Eventually you learn to integrate the knowledge you have into how you approach things - he has a potion, so I need to be able to burst him for this much or count on him using it....hmm....maybe I can pretend to try to kill him to get him to blow the potion and waste the money....and now you're a better player.
Bad? I just don't see it, because I know it works.
The reason why is that for me it dumbs the game down to a "if he gets x, then I'll get y" and "if he does x, I can counter that with y"
It was never that simple, but even if it was - ok, so what? If Demigod A got X, you can get Y to counter it. So....what about Demigod B and C (or sometimes D and/or E) on the other team? You aren't countering them. And this is how it should be because Demigod is a TEAM game. You should be able to get counters for one person - but if they're working together then your counter may just be negated or not effective at all against the other people. That's strategy, and team work.
I'm against the idea, I can see confrontations devolving into mechanical affairs, where I know what you're going to do, and you know what I'm going to do at every step of the encounter.
If everyone is good this is very much what happens now, and especially in 1v1 situations. I know what skills you got and what your HP is, and have a rough idea of your mana and items. If I've seen you use a potion at any time before duing the game I'm going to assume you have another and I'm not going to overcommit. You are doing the same for me. Stalemate in 1v1? Yep. That's why you run with other heroes and 2v1 people. Their carefully timed run and potion falls apart under the dps of 2 people.
Still not an argument against it, imo.