It's not just playing for status... it's also playing for promotions including shopping sprees.

If you've ever been invited to a shopping spree you know that you have a "base offer" plus you can get increased "shopping dollars" (my term) for additional play.

For example, your "offer" might be something like this:
Get $1,000 of shopping dollars in the Forum Shops, but if you earn 9,000 tier points you will get an additional $500 of shopping dollars.