For one thing, if an ability has restrictions on it, then yes, I'm going to say that the person using that ability has to abide by those restrictions. Second, as long as I'm being anal retentive, Doppelgangers don't even qualify for Racial Emulation because they're not Changelings (as being a Changeling is the sole prerequisite for the feat), so a Doppelganger Hammer of Moradin already wouldn't work. Not that this is anywhere near the most anal-retentive dispute I've ever seen on this or the other board.
I know that there are actual real people outside the height and weight ranges described in the PHB, but since when has reality had anything to do with the way things work in the game? No real person has a 40' vertical leap, but it's not too hard to build a character who has one. What the rules actually say-- the rules I presume we generally abide by-- on PHB 109 is "Choose your character's height and weight from the ranges mentioned on the appropriate race description (see Chapter 2) or from the ranges found on Table 6-6". The table has wider ranges, so I went with that to be generous, and Changelings are still too tall.
I'm not saying there aren't potential work-arounds either. Minor Change Shape is ambiguous enough that you could mimic, for instance, a half-minotaur gnome, which is a medium creature. (Being based on Disguise Self, templates aren't off-limits.) My point is that there are legitimate reasons to believe it's not as simple as Lycanthromancer made it sound.