generally comparing your game to one or two other games is not a good idea; it immediately marks your game as unoriginal/derivative
Originality is....to a certain extent....a myth.
Do you really think most popular works are truly original?
No, all of them have inspirations from other works.
Even Shakespeare adapted his works from older, common stories, or so I'm told, and in turn, many works from derived from his ideas.
But I can assure you I haven't seen anyone really pull off this idea before, these two other games are quite simply the closet I've ever seen come close to that, and they certainly have a lot that could be learned from. Thus, there's still some originality, but with plenty of inspiration from good ideas.
And if doing this is so wrong, why is it hollywood makes so many sequels and such, and they sell....really well?
Execution by a good director is of course critical too (often what makes so many other movies fail.), but that's the point, it matters more how you do it, more then it matters what you do.....as long as it's not a half-baked idea. And I've thought out a lot more to this idea then your aware, it's not half-baked.
The problem is that to anyone who hasn't ever played or heard of Valkyria Chronicles or Dungeon Siege, this pitch means absolutely nothing. When you're at a show like PAX, and have 5 seconds to grab someone's attention, saying "X meets Y" isn't going to do it. They'll space out and look at something else that's caught their eye. The "Die Hard on an X" trope also tends to be very limiting due to the literal nature of it. People may think, "Oh so it has Bruce Willis?" or similar narrow-scoped thoughts. There are a hundred different ways this description can be interpreted, and none of them give a clear picture about what the game is, how it plays, or why you're passionate about making it.
Working off your descriptive paragraph, if you eliminate the references to other games and clean up the grammar a little, this is what your pitch looks like:
A World War II RPG/RTS hybrid, where you only control a single platoon of 20-25 people, each with significant backstory and a long list of traits, stats, their own adjustable equipment, and LOTS of automatic weapons.
See how clean that is? Now people know what you're talking about. We've got a genre, we've got a setting, and we've got a clear picture in our mind of how this game is going to play. The point is to focus, and have a clear understanding of what you're making. No one will understand your game if you don't.
If it's only a single sentence one gets, screw them all. That premise is wrong.
That sentence is just as loaded with things for a person being required to know, as anything else.
Edit: None of these other pitches have remotely interested me, I need to know....more.......pictures, descriptions, something.