I think the MAIN usefulness of talking about modes in this forum, or any forum, is that it opens people's eyes. A lot of people strum or sing away in major or minor, but there's so much more to the world than that.

Even thinking consistently in the "aeolian mode" will sound different to thinking in a minor key (a lot of minor pieces sharpen the leading note - if you stick to the aeolian mode, you don't do that, you keep a tone between the leading note and the tonic, and just that one alteration can give a whole different feel).

The modes give a way of thinking about music which are more than just the major and minor scales. Yes, there are important historic reasons for studying them, but I think the main reason I like to talk about them and get people thinking about them is that they're mind expanding in quite a significant way.

The same can also be said of pentatonic scales etc, which also have a mind expanding quality, but the original question here was about modes, so I've such to that.

I'll try an analogy: Playing in ONLY major or minor keys, and never playing in modes or anything else is like saying "there is only 4/4 and 6/8 time", and not being aware of all the other permutations of timing.

But there's also a very practical point to all this, and as for whether I think musicians ought to be more aware of this kind of thing - absolutely YES they should! On two occasions now in the past year I've sung mixolydian songs starting on D, and found someone joining in with a guitar, strumming chords of Dmajor and Amajor, not realising that the Amajor chord includes a C# that obliterates the mixolydian character of the song and clashes with the way I was singing the melody.