Bear in mind,
tx_extra is used by (at least):
- every tx for the tx shared secret
- pools and miners as extra nonce
- certain other txs (like multisig and multi-dest subaddress txs)
Thus "removal" is not possible without catering for alternative ways to accomplish above. That's not to say we shouldn't discuss, just that it would be a big change affecting both the Monero codebase and other things like pool/miner implementations.
There have been a couple of alternative suggestions to blanket removal of
tx_extra, such as a fixed (or quantized) size with encrypted data, though that of course has other implications (bigger txs, slower parsing etc).
Low-hanging fruit for removal of another possible fingerprinting "feature" would be removal of the