The UASF isn't even really a soft fork, since clients that don't use it won't be able to validate the new transactions. The hard fork is just to increase the block size which was the plan from the very beginning and what the whole 2 year old dispute has been about: The powers that be/establishment/illuminati/NWO/Whateveryouwannacallthem have been trying to restrict the blocksize for two years to choke the amount of transactions and make the chain only available to people paying high fees so they can force everyone onto a layer 2 solution of their creation that they patented - basically ruining bitcoin.
The HF will prevent all that nonsense. Now we'll be able to have thousands more transactions per block which will drop fees back to pennies instead of dollars.