why would they want to avoid being complaint with a standard. That doesn't make any sense. did they just do a "roll your own" kind of thing and think it's better for some reason? almost every other wallet is compliant they aren't. go figure.
This what the developers or at least the author of electrum's official documentation say about that matter:
https://electrum.readthedocs.io/en/latest/seedphrase.html#motivationIn short, yes "
it's better" for them but not in a "
roll your own" way because BIP39 was just new before they implemented v2.0 electrum seed.