They might have conventions, or you've picked a fight weekend. I picked a random-ish weeknight in December:

LAS Homewood Suites: $110 on MVP rate
Tropicana: $40 (+$35 resort fee) on MVP rate
HGVC on Paradise: $123 (+$25 resort fee)

So it doesn't seem to me that the Trop is universally more expensive than HGVCs. I pulled up more random dates from November and the Trop is running anywhere from $308 to $61 (pre-resort fee). The bottom line is it's a Strip hotel, even if it is a lower-end one, so while you can get it on a good rate, and the F/B credit and stay credit can make it an OK option for Hilton loyalists if you don't mind that this is not the Waldorf Astoria, room rates at the lower tier properties can also spike badly if a convention or a popular weekend to visit is sucking up a lot of empty rooms.