How would waypoints deal with time? Unless you have SLB trudging through the wilderness counts towards the 90/180/etc day corruption time a lot more than not.
Also waypoints at those points would almost make the fact that Guth gives out potions for the big boss corpses - not a huge deal but currently it feels like I have to trade something (time, possibility of losing the corpse) for the PoCC. Dunno, maybe they should be easier to get. However I envision getting one corpse, trading it in, using the potion to kill the next boss, repeat. But that's just me.
Most of those places you mentioned already have shortcuts in/out. HMV has the wilderness exit (can you even imagine having to through small cave and UD every time? ug.) and the casino is pretty close to D32. I'm just not sure that instant travel to Terinyo should be a thing.
I'm of the opinion that the DH/Forest choice is now, and should remain, important. Going back between dwarftown and the objectives (quest, portal, khelly, graveyard) below DH/Forest frequently shouldn't be a cakewalk.
Completed: All Races, All Classes. Twice.
Fastest Run: Dwarf Mindcrafter - 34803 turns. No wand of tele.
Challenge Games: C- CK (stupid ending), Platinum Girdle x10, Westside Story, Team Teleport - illiterate troll barb, Scroll of Omnipotence obtained
ULE - DE Archer