This whole discussion is why they've brought in the Unbound armies option.
It's not about adding a whole new list of rules, it's about removing restrictions. Unbound armies to me (and i think a lot of players, particularly the older ones here will agree) is about being a bit more free to come up with interesting ideas for scenarios or army lists. Using another race's DTs sounds like an awesome idea, so does finding your SM army has just come accross the annual howling banshee convention whilst out on a recon mission, or your orks have intercepted an Astra Millitarum attilery column being guarded by 250 lowly conscripts or... It's just about creating "what if?" scenarios. It's about freeing players to come up with their own set of house rules with their regular opponents, it is not about competitive play.
The spirit of the rules does not seem to be about finally being able to spam out a narrow selection of units inorder to win every game in 2 turns. That sort of shit would get very boring VERY quickly. For everyone involved. And players who insist on playing those armies are going to find themselves short of opponents willing to play against them. All this talk of having someone spring a killer combo on you out of nowhere, play against it once, then just ask if they have an allternative list or ask for a rematch but swapping armies. Also (this doesn't seem to have been mentioned allready) i doubt any tournament is going to be allowing unbound armies any time soon and even when they do there's going to be a LONG list of custom restrictions.
Free your minds young ones, step away from the rules and your desire to find out who's better at finding exploits in the rules and remember what it was like to have fun playing the hobby you love. (Or just continue to play against opponents using the FOC if that's your bag).
My Complete DA collection
That's me breathing fire in my avatar, my aim was a bit off to start but i got all those orks in the end!