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.