You can buy many times more resale points for $30K! The only benefits you'll miss out on by not upgrading with the developer is getting to HGVC elite status with gold or diamond Honors status and a few other benefits that are not worth the price. (I can't even remember them since they aren't of value to me, but check the members' guide for the list.)
If Hilton Honors status with its corresponding benefits at hotels is important to you and you don't stay enough to earn it (in which case, the benefits won't be that valuable to you), get a Hilton Amex card. $20,000 spending a year will get you gold; $40,000 on the Surpass card will get you diamond.