Not true, I'm fine with a pre-created player. That's how it often is in other games like NBA story mode. And I'm great with a fixed storyline so long as there are branches to that tree based upon what you say, your decisions and how you play.
But yeah, being able to play in the NFL would be ideal. It's going to be sort of odd to put so much heart and soul into a character, get draft and then...that is it, its over.
I would hope at least EA will read your Madden 18 save file if they continue the story into Madden 19 so our hard work, our choices and such are not for nothing when/if we finally are able to play in the NFL.