Solo shuffle just needed to have its own rewards, arena should of kept it’s rewards and that way there would be a reason for people of all skill levels to do them all.
And of course there is easily an argument for arena to have more or a better version of the rewards as it requires more effort simply through requiring socializing.
Already have 6 recolors of the same set, they could easily add a 7th. I know they act like it is but I can’t imagine designing more tabards/cloaks/enchants + an additional mount is a huge investment in development resources.
Rewards drive participation in everything game related, like it or not. And you need that at the top end as well as the bottom/mid end. Adding more rewards fixes everything when it comes to participation.