Is it worth to kill weekly bosses for 60 resin if I don't need their talent level-up drops anymore?

The only reason to do the weekly bosses are the billets, their talent drops (and Dream Solvent to swap them). If you aren't in need of any of these, you can very well do other things with higher yield:

Artifacts (Gladiators and Wanderers Troupe) and character ascension materials(gems): Farm normal bosses for 40 instead of 60 resin. They also drop more specific character ascension matherials of one chosen element.

Do the 30-reson bosses and if you're not in hard need for billets, farm normal bosses or do domains instead of the 60-resin-bosses. I'd recommend to take the 3 30-resin-fights and leave the rest. You should choose which 3 you take in needs of current or future characters.

After all, you can only do each weekly boss once weekly, so it's pretty hard to farm the talent materials if you need them and don't already have them.

If you still lack billets (12% chance) or dream solvent (33% chance), it's kinda worth it since you can't get them anywhere else, but otherwise, not so much, since it only gives small amount of artifacts (average 4.1/2.9/1.2 3?/4?/5?) compared to doing artifact domains 3 times (average 10.7/7.4/3.2 3?/4?/5?). Well, you also get on average about 12 slivers per weekly boss, but that's not valuable enough to be worth it as a goal.

No, it is actively a suboptimal choice as you could choose to go for specific drops with that resin instead.

When you use https://traveler.gg/domain-and-boss-loot-drop-rates/ to compare drop rates, you will notice that billets and dream solvent are already factored in the overall value — which is a consistent resin value compared to other resin options. Since you don't want them, you are losing out on a small amount of value by doing them.

Resin is what gets you things in Geshin Impact. If you spend your resin on something, you can't spend it on something else. This is a tangabile opportunity cost that you will incur every week if you choose to do these bosses. Your steady weekly resin gain is 1260 units. Each weekly boss clear removes almost 5% of your available funds for that week that you could otherwise spend on activities that provide you the resources you actually need to accomplish your goals.

You are already receiving a steady supply of both billets and Dream Solvent by doing the discounted weekly bosses. You will want to take advantage of the discounted weekly bosses in the future. If you gain additonal material now, you reduce the value of the future material that you gain then since there are finite use cases for billets and Dream Solvents.

You are slowing down the space of gaining material that you want now that you would use to accomplish the goals that you want to realise for your account by accumulating a less targeted increase of resources instead of a specific increase in resources, so realising your account goals slows down.

If you enjoy clearing the bosses, you can always do so without collecting their rewards.