I've been turning this mode thing over in my head. Maybe since this thread is going, someone can help me suss this out. Also, since we are discussing B dorian, let's stick with that.
So B dorian uses all the same notes, in the same order as the A major parent scale. It just has a different starting point - the "B". So I'm thinking, the only thing that makes a dorian SOUND dorian is the way you sequence the notes.
If the different modes uses all the same notes, why should it matter if you learn it by whole steps and halfsteps or just as an A major scale that starts on the "B"? The finger pattern for a dorian scale is always the same no matter what the starting note is (which I'm guessing "is" knowing the W/H step pattern, essentially).
I know there is some discussion as to how to approach learning modes, but I'm ultimately concerned with modal application (how do you actually use this stuff) and I think I have some conceptual errors that needs clearing up.
Because "learning" or "knowing" a scale or mode has very very little to do with how to finger it. That's simply the least important part. For me, what "knowing a scale" means at the very least is:
A. You know what it sounds like- you can sing the next note before you play it. This is music, not a physical exercise and the scale is totally independent of the instrument used to execute it.
B. You understand its construction- you know the whole-step/half-step construction because that's how you build the scale. You know the intervals that make it Dorian instead of Aeolian.
C. You can find it on your instrument no matter where you're starting from.
It's simply false that " The finger pattern for a dorian scale is always the same no matter what the starting note is...". That's because the fingering pattern for dorian depends entirely upon what you're going to use it for. To USE a scale/mode, you don't want to be limited to starting and ending on the root. It's about the way the notes go together, not where you play them. So if I'm clearly in B Dorian, I'm not going to limit myself by only knowing where those notes are in one position on the neck, nor by only having one fingering pattern to play them. It's the SOUND of Dorian that makes it useful, not the fact that it happens to be an A major scale started sideways.
That's why most modal instruction is so very awful for players. They're told that "modes are the answer" and then the presentation is JUST mysterious enough that it sounds like the answer to everything, but simple enough that they can figure out a very rudimentary way to play them.
BUT- in the example of ii7 V7 I progressions, when someone says to use (using Dmin7 G7 Cmaj7 as the example) D Dorian then G Mixolydian then C Ionian they're telling you to ignore all the things that make those three chords work together. Those three chords are related to each other from the parent scale of C major, they are a unit of three, not three disparate entities. And thinking of three different scales (even if related) leads to ignoring a fundamental part of our job as bassists.
Half of our job is to DEFINE the harmony. If we're thinking of a ii V I as three separate chords instead of thinking of them as a progression of three related chords in one key, then we're not defining that harmony. That's why (unless you're playing modal music- e.g. some Miles stuff, or an two chord vamp like ||

min7|G7:||
*, you need to focus first on what's in the chords, then how the notes in THIS chord relate to the NEXT chord.
Note that no one who seriously promotes chord tones over modes for this stuff has ever suggested that one only use chord tones! No, it's about knowing the notes of the chord so you have your primary targets at hand. Then the passing tones can be other notes that sound good. And most of those "sound good" passing tones will be from the scale of the tonic. Yes, you do get to the same notes as thinking separate modes. BUT, first using one scale and knowing the chord tones is a lot less mental gymnastics, and second, you're able to organize the choices coherently over all three chords rather than switching gears.
* the reason a two chord vamp like ||

min7|G7:|| isn't a ii V is because as a two chord vamp, it never goes to the C chord so there's no pull to that tonic. In this case I'd be thinking D Dorian over both chords (of course it depends on the melody! It could easily be G mixolydian) as my starting point, but I'd still have to be aware of the chord tones.
And knowing the chord tones AND understanding the harmonized scale makes understanding the modes so much more apparent and useful. If you understand the harmonized scale then it's really obvious how Dorian differs from Aeolian even though they both go with minor chords.
John