I just seems kind of strange that something like Session Drummer 3 has a graphic interface that looks in every way like a fancy hardware drum machine, pads and all.

But, contrary to what you can do with hardware, you can't record from this one. I don't see the point of having the patterns set up the way they are if it's just to audition them. Any browser could do that. These buttons kind of scream live performance but, even though it will work for that, you can't record your performance. The only way to record a performance is to own and use a midi keyboard.

For the audio, since it is being generated anyway, it seems to me it would be nice to be able to record it to an audio track, just like if the audio was coming from an interface. How hard could that be to implement ?

I'm sure my thoughts are nothing new in this matter, it's just new to me.

Paul P,I could not disagree more. All the major drum VSTs behave exactly in the same way, all of them. You drag the MIDI-loops onto a MIDI-track and that's it, edit them or record your own. That's the industry standard, regarded best by most.
 
Also, practically all soft synths behave the same way: There's a virtual keyboard for testing the sounds, but none of them (?) allows you to record that keyboard. IMO, you're saying that the most unpractical, amateurish and clumsy method should be made a starting point. You can do that mouse clicking in the PRV in a controlled way with visual feedback of the results.
 
You can't even control velocity with a mouse (or are there velocity sensitive mice?). Have you ever tried to click a mouse to metronome beat? 16th note hihats? The mechanical structure of mice is not designed for such accuracy.
 
Have you ever tried recording drums with a MIDI-keyboard? You can record easily three (say, kick, snare, hihat) instruments simultaneously (more with practice) with a real swing and feel.
 
Of course you are fully entitled to your opinion, and that's 100% ok, but it seems to me you're favouring a poor method 'cause you're not familiar with the good one.

Kalle, you're right, it wouldn't be great, especially for individual hits of a drum kit.

But I'd still find it useful for quickly capturing an idea without pulling out the PRV, say while trying out sounds in a synth.
The audio track is just sitting there doing nothing, why not enable it for recording ?

Seems sort of intuitive to me.