I think you miss the point that Hariyama has great defensive stats (statistically similar to Azumarril, another slow CB user), great resistances (or still decent resistances + status immunity with guts), and the fact that he's slow means that it will be harder for the opponent to take advantage of defense drops. It's not like you're planning to stay in with a CB user.
Furthermore, Stone Edge or Ice Punch or Payback give it terrific neutral coverage, enough so that it can fit things like Bullet Punch or Toxic into its set if it wanted to screw with opponents even more.
So maybe it's not a Scizor or TTar, or even Starapter or Gallade, but I've always thought a full-force offensive hariyama had a place in UU-- think I'll be giving it a shot.
Azumarill is good with CB because of its priority--without that I doubt that CB would be a popular choice (I noticed it is currently losing favor, also to the subpunching set). This is again the case with something like Scizor. What's bad about Hariyama is that after one CC its basically a must-switch situation, and you will have to sponge hits before you can pull the CC off in the first place. While I guess this could work IMO it's not very efficient. I guess I'm kind of knocking it before I try it, which is bad behavior. So, I encourage you to try it out and I hope to hear some positive news about it.