I think that Flash is pretty useful in low-level fights in-game where you're pretty outlevelled because it's your first time playing the game. I usually put it on my Abra / Kadabra to fill up a slot while I'm going through the game for the first time.
Everyone knows Teleport is worthless.
At least Flash is better than DeFog, its DS replacement.
Umm...no, just no. Flash is not good by any stretch of imagination. Sand-Attack was crappy enough, but relying on a move that might make your opponent miss which also has the chance of missing itself? That's way too many 'if's to be even remotely useful. x.O What the Abra line needs for fillers is special attacks like Shock Wave, Energy Ball etc. If they don't KO or incapacitate what they attack they're pretty much dead anyway. As for De-Fog; it's not a replacement for Flash, it's just another freaking crappy HM to add to the collection. x.x Flash was demoted to a nomi-HM, but there are Flash places in D/P too, just not as many of them. :\
But yeah, agreeing with Chibi-chan: if they want HMs used they should actually make the moves themselves not suck. (Thus far, the only ones that have succeeded in this regard are Surf and Waterfall, although the new and slightly improved Rock Smash is sometimes used to cover up for crappy movepools). Cut, Fly, Strength, Flash and Defog all remain utter garbage, though. Incidentally, Cut is the only HM with an optional overworld use (Excluding the one-place-only effects of Flash and Rock Smash (Used to open the paths to Registeel and Regirock respectively)), but there are also the nomi-HM moves Teleport (Essentially a more conditional Fly), Dig (Free Escape Rope effect), and Sweet Scent (Gives you an instant wild pokémon encounter if you are in a place where they appear, which, might I add, comes in very handy in the Safari Zone since it doesn't count as taking a step ;3). But you know, these are people who (ingame) advertise the elemental hyper beams (Blast Burn, Hydro Cannon and Frenzy Plant) as the schmexiest moves ever. They might honestly have thought that the HMs would be useful. o.o
Concerning Hyper Cutter...it's sort of very pointless. I mean, who cuts grass anyway? If you don't want the encounters, invest in some freakin' Max Repels or give your lead pokémon a Smoke Ball. Tropius + Gyarados is all you should ever want for your HM needs.