For a long time, I never used a torque wrench, and just went by feel. Then (and being honest here because I love good tools) I went out and got a decent one. I've used it more on the car than anything else, but even then if I'm in a hurry and assuming its not the engine block (don't want to warp the head thanks!) I tend to just wing it. Whatever you feel comfortable with is fine by me -and if you think you have (or have) no mechanical feel, I most definitely could see it being necessary.
While usually a bike not an investment of similar financial magnitude as a car, I can say I'd certainly hesitate buying a car from someone who claims they rebuilt the engine with no torque wrench versus a person who does (and of course there are other factors, but all things equal, etc). And maybe that says it all -if I was buying a really really expensive bike I'd be much more comfortable knowing the mechanicky person who worked on it used a good torque wrench.
The place where I'd most certainly want a torque wrench though is carbon fibre; wouldn't like to accidentally over tighten that, and if I had a CF frame (which I don't) I'd definitely be using a good torque wrench on that -my opinion is you need one then. So, even though I don't really use one that much, I'm giving two thumbs up to it

Horses for courses......