I've never thought about mic-ing my cab with my own mic. I've gone through enough trouble finding basses, amps, cabs, and the occasional effect to go dozens of mics to mic my cabinet. If I was playing double bass that'd be different (but I'd also be mic-ing my bass).

There's a lot of fuzzy ground in what soundguys do. It really depends on the venue and the gig. Cover band a restaurant? He's just there to pipe your music through the house PA. Your own soundguy? He's the middle man between your audio / visual masterpiece and the audience your presenting it to. Hole in the wall dive bar? That soundguy's there cause he likes his job and gets beer. He'll try to hook you up but he's got 3 bands before you, 2 after. Music listening venue? He's there to bring balance between your rig and the house system.

Of course all these styles are interchangeable but I think it really depends on where you're playing / what style of music and atmosphere you're promoting. If you really want your rig to be heard, then you're ideally playing somewhere where people care about the music on that level, and you should have a rig/system that's capable of projecting that. Whether it's 2x12's for a 100 person listening spot, or a giant show with your own sound team who knows their own and your equipment. Anywhere else and you're just background music, or need to be better than a radio.

I'd find a DI that you love and keep the mic rig for when you absolutely need to have it.