Very few people explore other browsers? Alt browsers are often the first app that people download. Chrome is included in gapps.
Which people? I'll grant that Chrome is an exception, given that it's bundled, but I've never seen usage number of other alternative Android browsers hit any meaningful numbers.
Not saying I agree with the Malware comment, though the bundling is annoying.
The first thing I install on my gf's computer or phone is Firefox and configure it to sensible settings (turn off third-party cookies, install ABP and Ghostery and stuff like that).