As not_bob mentioned, it's useful.

I2P+ comes with feature rich console interface, one that also happens to be a great place for beginners to start out - doesn't mean users would need to keep the outproxy.

Some otherwise might not have opportunity to try outproxy (some lazy, some unsure how).

And having access to browse clearnet also means a user is more likely to keep an i2p browser (in turn, i2prouter) set up - this means more traffic for all of us. And that's good for all.

In this way, I'd say it's a win win, to have built in (by default, not required to keep).