Should I ask seller for credit towards this?

Talk to your realtor. In the purchase offer you can do whatever you like.

What happens is that sometimes a seller will say OK, I will allow an offset to fix the roof, it is 20 years old and worn out, but I won't discount the house 10k, I will let the escrow company hold the funds and dispense them to a roofing company after the job is completed.

Does that really matter, I don't think so, seller is still getting 10k less, just they feel like if buyer does not really want roof fixed they may counter and say OK, how about a 5k discount and no off-set.

On any home over say 10 years old you could say, floor is worn, appliances are 10 years old, landscaping is old, needs painting inside, etc. .....How about you sell me the house for 300k, so I can do 100k of updates.

Being funny, but why not? The reason is the seller says 400k is the value, take it or leave it.

As a seller, you can ask, but I would say no.

The items you listed in the other post that were found in the inspection you should ask for. However, the flooring issue didn't change from when you made the offer. If this was a big deal, you should have ask for a credit when you made the offer.

Ask for whatever you like. A couple K to redo the floors isn't worth the deal falling apart on either end.