Im halfway to getting my first one, and the more I think about it the more I think 100 maps is too many, there are 15 careers so thats 1500 legend + champ runs to get all of the helmets which assuming the average map takes you 20-30 min thats 750 hours. I understand they are an end goal to work towards but I think 50 is considerably more reasonable because we always have really time consuming stuff like 500 deeds to do if we manage to finish all the hats which at 50 games per would still be 350 hours. Not to mention reds and cosmetics are still rare and you can still get duplicates (of reds), and you can still never find that one perfect one you want.
Lots of players self included are running out of steam in this pointless grindfest. I like the legend challenges, thats great, sorta like the hardcore achieves for v1, im always up for stuff like that, but the RNG ontop of RNG on top of RNG mixed with Korean MMO style grinding a1ds is just too much.