Plus, why not have two choices for address formats for Electrum Segwit wallets, one for Bech32 and the other for the more common "3 addresses"?
There is no limitation on sending to or from Bech32 <-> P2PKH or a P2SH. The limitation is whether or not the other wallet supports it or not. So from Electrum you can send and receive both ways. Core, on the other hand, is not Bech32 ready yet so it will not let you enter a Bech32 address to send to. I have been able to send from a Bech32 to sites using Core with no problems. I have been told that Coinbase, for some unearthly reason, is actively blocking deposits from Bech32 addresses but I haven't heard of anyone else doing so.
Core 0.16.0 should be out very soon and then full Bech32 support should be more common.
I think the reason Electrum only supports Bech32 Segwit addresses is that using the "3 addresses" was only ever intended as a tempory solution and they decided to skip that step and go straight to the end point everyone else will eventually arrive at.