If you transition your email workflow to full featured-clients you'll use encryption more often, and discover the gaps in Mailvelope's feature set when you send an encrypted email out to three people and everybody can read it except the Mailvelope user.
Mailvelope will be able to replicate the entire feature set of any desktop client within a year and I am going to implement an optional deterministic keygen for better keypair portability. We've had wonderful, full featured clients for over ten years for PGP and less than 0.1 percent of all email traffic is encrypted. I want a mainstream product that many people will use.
This just isn't true. Sometimes you need to do something like email a password or private information to a friend. I don't want to spend half an hour telling them how to configure an email client to use PGP. Everybody want the batteries included. I can have an encrypted convo with my friends using mailvelope without an issues at all. Yes I can't do multiparty nor can I sign. These will be corrected soon enough.