mwgdrwg
Be a Pisces. Jam.
12 seconds? That is an unusual length of time to launch an app.
Anyway, it isn't something that's ever bothered me. I'm playing a game, a notification comes up. Either I think "oh that looks interesting, sod the game I'll go read the email", or I think "oh just another stupid notification, I'll look at it later maybe". I can only ever use one app at a time, I can't play solitaire at the same time as read mail.
This is very much the case on my desktop too. I don't actually need my mail app open all the time, all I want is notification of new mail and the option to switch over if it looks important. I do use multiple apps at once but those tend to be things I couldn't practically do on a mobile device anyway (BBEdit and Pixelmator and Transmit to do code/images/ftp for web design for instance).
For other users multitasking is essential and it is a strange decision to disable them in this way. I don't ever browse/email/im without spotify or last.fm in the background, for example.