As a GM I would love for my players to ignore these tiniest shittiest items that don't deserve the brain power needed to write the name of the item on their character sheet.
There are two economies in the game that talismans fit into.
Long term multiple levels and dozens of battles:
Why would a PC use that level 14 consumable that you could sell it for 450 gold and get a lvl 8 permanent?
They can buy a +1 resilient armor when they should be at +2 greater resilient armor (2 "steps" behind).
Or they could buy a greater staff of fire. Yeah the players got rid of that back at 10th level when they upgraded to the lvl 10 staff of evocation.
They could buy a wand of smoldering fireballs with money and get a truly free fireball that doesnt take recharging... now your 14th level caster can get spend actions to cast 1d6 persistent damage attacks once per day.
Players will be drowning in magic items in PF2.
The 14th level character on average out of a party of 4 will have based on what was given out from page 509...
Permanent Items: 15, 13, 13, 11, 11, 11, 9, 9, 7, 7...
Consumables: 15, 13, 13, 13, 11, 11, 11, 9, 9, 9...
Gold on top of the above to go buy further permanent items: 7,043 not including the other permanent items above that they didn't want.
I'm not seeing the importance of getting that extra 450 gold / 8th lvl permanent item whose power level has been outdated for several levels. If anything I see the reverse happening. In the above scenario sell your outdated staff of fire to buy 4 Grim Trophies or 3 Murderer's Knots and you use them on elites and bosses.
Short Term single combat. You get 3 actions a round. You aren't going to be spending that on low level action items. You need to be as efficient as possible with them and that is what talismans improve upon. They arent intended to be powerful and worthwhile on their own. You might as well complain that non magic daggers aren't powerful.
Now a case could be made that the 31 DC at 14th level is too low. That's different though than a horrible system that offends you that others like it.