My sense is that if it is admitted by core devs to have been a mistake. Node runners will start to question whether other changes currently being proposed are also mistakes and they lose this aura of being the benevolent high priests of the Bitcoin protocol.

That could be part, at least subconsciously. No one likes being wrong, or losing some reputation. What's the deal with lightning and the witness discount? Someone said somewhere that lightning needs it, but I'm not nearly techy enough to know the truth of it.

No one *needs* the witness discount, they would just pay the same as for non-witness data. And the block size would be reduced back to 1MB.

The reason it was introduced was to get an effective block size increase and incentivize utxo consolidation - which turned out to be completely wrong. The utxo set exploded instead. Oops.