Craig,
I'm sorry, but I think you're kind of missing the point. I mean no offence at all, but you not feeling the need for an LFO plugin that can be used to control any MIDI accessible control in a DAW, including the "mixer functions", doesn't mean others don't or that you can achieve the same results by drawing envelopes.
I can think of quite a few uses for such a thing, and I'm certain someone with more imagination than me (and there are millions of such people out there) will come up with lots of uses that never occur to me.
Envelopes. Yes, it's possible to draw regular LFO-like functions as envelopes. Sort of. But if you want to experiment with different wave-forms, different LFO frequencies or simply change the envelope it involves a lot of work. And there are things that are seriously difficult to try and do by drawing envelopes.
Here's one example.
Let's say I decide I want a sine curve modulating a "widget controller" over two bars. OK, I can draw that. It's a bit of a pain if I want to try it over four bars as well, but let's assume two bars does the trick.
I now think "what would happen if I tried a frequency modulation on that envelope? How about a rising sawtooth over a period of an eighth note but with low amplitude? OK, let's try making that another sine instead.... and how about I ramp up the speed so the original wave period becomes two bars in this section.....?"
Drawing that kind of thing is slow at best and involves an awful lot of maths to work out the shape of the wave at best.
Use an LFO that can itself be modulated by another LFO and it becomes simple. Or at least the only difficulty becomes getting the LFO settings right, not drawing and re-drawing complex (or even simple) wave-forms.
And that's just scratching the surface. Not everyone thinks in tems of "a guitar sounds like and does "this", a piano sounds like and does "that"". And as for "whooshing" not being to your taste, millions of guitarists, synthesists and record buyers clearly disagree about that. Personal taste shouldn't enter into whether what someone finds a musically useful tool is provided or not.
Developing something like Logic's MIDI LFO and envelope plugin shouldn't be too onerous I would have thought. It's not even like it needs to be able to generate a sound. Be useful if it used more than the "ordinary" 128 7-bit MIDI steps though, maybe 14-bit instead. Not that 14 bits worth of values is likely to be needed, just something smoother than 128 to avoid the stepping problem.