Because the character beat of replacing a legend is a good storytelling hook and a much more interesting premise than anything Barry had for years prior.
And it bared out pretty freaking well.
Asking how Wally is different from Barry is about as tiresome as calling Barry boring.
They consider different things because of course they do. Saying that they didn't go with Ryan and that shows how little they viewed Wally is silly because it was shot down for a reason just as much as it was considered.
Someone literally linked Marv Wolfman expressly stating that there was a consensus thinking Barry was boring, even though he didn't agree. Talking like this is needlessly condescending. Do you think all history scholars are fools because they didn't live in the eras they know about and are interested in? Is it so weird to you that a comic fan is familiar with the history of the hobby they love?