Sure you can use pads to trigger MIDI, and it could does the job like a charm, and it could be adapted to your workflow, too.
I personally use Maschine sometimes, it makes me feel fresh from the traditional piano pattern where I always look for that note or another. It can be fun to play, too.
Was just saying that basically you can buy pad/knob keyboard to have everything in hand. IMHO keyboard just enable efficiency when it comes to harmonise or play complex chords (5/6 notes, like gospel/soul/jazz ones), it makes sense when you need to quickly find notes. But you're right, some practice/theory behind piano may be necessary to use it effectively.
Yeah I find synthesis-based synths much less related to the way you play it than it is for sample-based ones. What synthesis gives is a wide choices of possibilities to you for arrange the way it sounds, velocity, articulation, etc.
On sample-based ones, you can't that much control the way samples are triggered. MIDI can inform the synth which sample trigger, and this is why now some virtual samples synths can create such great simulation of real articulations/groove/sound.
Depending on what kind of music you want to do, also. Keyboard is so flexible, I just can't stop loving it ahah.