"Degraded" because of most of the features of the original genre have atrophied, you're left with a limited experience. Not "pure" cause this was supposed to be a shoot'em up, not a dodge'em up. A more fitting comparison would be a racism game completely about switching gears: yeah you're still in a racing car and it's very hard to get it always right, but we were supposed to go driving actually.
Original game? What original game?
Shooters as far as I know began from simple games. With the time they've got elaborated. Smups are one of this elaborations - they are quite sophisticated with they own systems and gameplay formulas. They are definitely not degrading anything. In shmupas you need to think as fast as move. So it's very far form degradation of the genre or anything.
would be a racism game
I am afraid to ask, but what is a "racism" game? :
