That's exactly it.
Misunderstanding how it works. I thought that your miners would be split between the two coins, jumping from one to the other, or whatever. But if you say that people merge mining will get the same amount of BTC as those using pools that are only mining BTC, then I'll stick with the merged mining.
Seems a bit hocus pocus to me, but I'll believe you. Hell, it was the original NMC run, way back, that paid for all my equipment, therefore I am very glad to be involved in it again

Unfortunately, the profitability of merged mining over normal Bitcoin mining has fallen quite a lot since it was first rolled out but it's still a nice bonus (about 3.6% right now). There was a period after merged mining became available that Namecoin mining was actually more profitable than Bitcoin mining (so the merged mining bonus was over 100%)! Namecoin difficulty is still rising fast so this bonus should continue to drop.