[sdiy] dumb wavetable question

[David G. Dixon]

All this talk about wavetables (which, I must confess, I've only skimmed for
lack of understanding most of what is being said) has left me with a few
questions.

What is the big draw of wavetable synthesis?  Is it:

1) to gain access to an infinitude of waveshape possibilities?
2) to overcome certain limitations inherent to analog VCOs?
3) to render MIDI/computer control more convenient?
4) all of the above?
5) some other reason?

It seems like the most complicated thing is to get the wavetable to play
exactly once within one period of the desired oscillation frequency, and the
wavetable part itself is in fact pretty trivial.  This leads to my real (and
potentially stupid) question:

Why not clock the wavetable with an analog clock driven by a conventional
expo converter?  Of course, the tracking would only be as good as the
exponential converter, but the wavetable could now be clocked with a plain
old binary counter, and the frequency would always be equal to the analog
clock frequency divided by the number of wavetable samples.  Since it's
analog, it could be glided and detuned smoothly, just like any other VCO.
Of course, you'd still need a MIDI-to-CV converter to control it digitally,
but that could be built in.

You'd need a current-controlled clock capable of top speeds of about 5MHz
(assuming wavetables with 256 samples) to cover the audio range.  Is this
doable?