SPS utility is absolutely one of the biggest lacking factors of the game. I completely agree. I think the devs thought that requiring SPS for Tournaments would ultimately be enough to keep its value high but unfortunately, tournaments in themselves just don't have that big of a draw to newer players. Simply put they are almost impossible to win without having many of the stronger UT cards which are an expensive buy in themselves.
I have a few other potential ideas related to SPS:
Implement the SPS governance function as planned. Require burning of the tokens to submit a proposal with the weight of the burn automatically counting towards in favor.
Tie ECR recharge to staked SPS. Currently we recharge 25% per hour. This would definitely require number crunching by the team's economics group but perhaps lowering the base ECR rate to 15%/hr and then providing a boost of 1%/hr per X staked SPS up to a max of 25%/hr.
Update the battle background/board to allow skins as well. The background can be split 50/50 and show the skins of each player. Further cosmetic NFTs can be added as needed to show off during battles. (Like bobbleheads that are on the side of the board etc)
Allow SPS to be burned at SPS/DEC market rate to upgrade guild buildings as if they were DEC.
Update market fee structure (5% of price paid by seller) to be paid in SPS. Further that SPS could be burned instead.
I second the idea of card skins being purchasable with SPS. I think for each expansion skins could have a 50/50 release paid in dec and sps. These and all other skins need to be tradable.
Create additional holdable titles that are related to or at least purchasable with SPS.
Provide a slight DEC boost per win to accounts with X SPS staked.