Why do a 10mm skeleton army for HOTT when you may find it next to impossible to find another person local to you who also has a desire to do 10mm HOTT
The trick's surely to do a couple of 10mm armies - skeletons and orcs, perhaps - so that you can provide both sides and then - if you find an opponent who enjoys the game - get them to paint up some armies and do bigger games with the orcs and skeletons on the same side. And so on - and then you can use the armies for Warmaster or Mayhem or Sword and Spear.
I think you're right about GW's success, but it's also true that the historical players tend to use the same armies for lots of different games - perhaps a DBA phase, then onto Impetus, then FOG, then ADLG, then back to DBA. So another part of GW's success is somehow convincing a certain portion of players that there's only one 'true' game to play with a given set of miniatures.
It's a bit odd, really; the players who skip from one ruleset to another (whether in phases or one game at a time) are probably getting much more out of their armies and a much broader range of gaming experience - plus the chance to compare rulesets and find what works best for them.
Oh - another potential use for your dwarf army:
Of Armies and Hordes from Ganesha Games. It's excellent and very innovative. You have to divide your table up into zones, but that's easily - and subtly - done with regular or scatter terrain. And you can use absolutely any basing, so it's perfect for getting huge numbers of different miniatures on the table together.
You can design your own units for it, but there are almost 700 unit types in the official lists. With 110+ different dwarf units, I think everything in your army is covered. Certainly, the gyrocopter, handgunners and slayers are, and you'd have several options for each of the other units.