Rough... So it's impossible to get all Pokemon from a single series now.
I liked it better with just Blue-Red on my old-school Game Boy...
I guess I'll just erase my games and start over.
My DS has wanted a Pokemon game for a while now, but that just deflated my excitement.
I won't fall prey to a vicious marketing ploy that requires me to buy new systems and a multitude of games just to have one perfect file.
Yep... Blue-Red here I come again!
Also, to answer your "simpler" question, yes you will certainly be missing out if you only buy FR/LG.
Collecting all of the Pokemon isn't the entire point of the games. Diamond and Pearl, aside from a new region to explore, provide Wi-Fi support. Not being able to battle/trade with friends across the internet would mean you would be missing out. In my opinion, at least.
While it isn't the entire point, I cannot play a game and not strive for perfect.
With Blue-Red, the old 151 was and is perfect.
The Wi-fi for D/P is what spurred me to start looking into the franchise again, but now I'm not too sure.