The origin of this story is, in its simplest form, that the merkle-proof message sends over a list of hashes and the definition if any hash is a leaf or a node is based on an assumption. An assumption that can go wrong should a transaction be an exact multiple of the hash-size.
The simplest solution is to avoid having such transactions.
The technically more correct solution is to fix the message-format for merkle-proofs and make things explicit there. A simple one byte addition per hash to indicate its type.
In future I’m sure that the message-format will change as the medium will change. People might start to send stuff over JSON as a simple example.
As such I’m quite optimisitic that as time goes on we fix this properly, in the right layer. It may take 10 years as communication layers are upgraded, but I do think that will happen. Probably in much less than 10 years.
And when that happens, there no longer is any need to forbid the 64 bytes tx.
Remember, the only reason this solution was picked is because it had practically zero impact.