There's oodles and more of interesting and challenging basslines in heavy metal. Some bands not so much, where the bass just follows guitar and nothing else. Too many bands to name them all feature imaginative virtuose and creative bass players, whose parts are not at all easily copyed. The fun in playing slow (laid-back) basic blues/rock for half an hour or more escapes me, it feels like a chore. Me I'd rather play thrilling fast rollercoaster parts, that keep me on my toes and demand my full attention when playing.
Just to name a few people that have me raise the bar for my own skills:
Frank Bello, Dan Lilker, Steve Harris, Paul Barker, Jo Bench, Frank Watkins, Phil Rind....
Listening to these people (and many others) makes me pick up my bass, try to play what they play and incorporate what I learn in my own songwriting.
On the other hand, 'great' bands like the Beatles, Rolling Stones, Yes, Genesis and many other millionsellers I can hardly bare to listen a single song of.
It takes all kinds apparently!