Well, actually, yes, but it depends if you talk about Fallout 1 or Fallout 2.
I've installed Fallout 2 with rp 1.2 few days ago and there is something that troubles me... I've got 8% in Steal skill (untagged) and I can steal everything. And I mean EVERYTHING. I am spotted maybe 20, 40% of times, which is ridiculous. I stole the 3 bozars from Buster's guards so easily that I turned off the game. Seriously, that's annoying. At NCR I had so much loot that I seriously thought about going straight to Frisco to get caps.
About Fallout 1... I don't know, I played it maybe six months ago. I can't write an accurate comment on it as I could for Fallout 2. I will install it again.
Edit : Honestly, I never used drugs, in Fallout 1 nor in Fallout 2 nor in Tactics. So changing them won't make the game harder (at least for me). About weight... Well, I really don't think it is the way to go, unless armors and pistols were ridiculously light. Reducing starting Carry Weight might be good, however.