Ben,
The test you describe is closer to an outright resolution test than an MTF test. The point of MTF testing is that it measures the contrast of a lens at a number of different spatial frequencies (spacings of the test pattern, IOW). If you look at the figure for 10 line-pairs-per-mm then you get a good idea of the contrast of the lens, while at 40lpmm a high figure indicates good resolving power for fine details. The old-style resolution test sets out to establish the finest spacing that the lens can pull any meaningful information out of, which is quite a different thing and isn't really as useful for assessing the real-world perforamance.
Your idea for comparing the colour rendition of different lenses is likely to run into trouble because there is no imaging system (based either on film or direct digital capture) that can faithfully portray the full range or gamut of colours that we perceive. Even for the colours that can be reproduced, there is always a bit of colour shift introduced by shortcomings of sensors and output devices. Colour profiling is supposed to compensate for these factors, but it's not perfect. Don't let that stop you from thinking about better ways of solving the problem though, you'll be rich and famous if you do, and a lot of photographers and reprographic people will warmly thank you! If you want to read up on the intricacies of colour theory, a good place to start is
http://www.color.org, which is the website of the International Color Consortium who define the worldwide standards for colour processing and reproduction. Be warned though, it's a deep subject.
Regarding your original question, there are many other criteria beside bokeh and basic MTF measurements that can be used to characterise a lens. If you really wanted a full picture of a lens's performance, you'd need to know the following (others please feel free to add anything I've forgotten)...
* MTF at all f-stops and across various focusing distances from infinity to closest
* Contour map of the plane of focus at those distances and for each f-stop
* Measurement of flare characteristics of the lens under a broad selection of lighting conditions
* Light transmission properties of the lens
* Measurement of light fall-off effect at all f-stops
* Measurement of field distortion at all f-stops
In practice it's not easy to achieve this. The multiple MTF measurements are too costly to gather and produce an inordinate amount of raw data. There is no agreed way of quantifying the flare characteristics of a lens, and it's hard to see how this could be tackled well. Bokeh and colour rendition are hard to quantify objectively, for reasons already discussed. Note that because no lens has a perfectly regular plane of focus (and the true shape is not easy to measure), this can create anomalies in the MTF results. Most testers set focus for the centre of the field, then measure the whole field at that setting. If the plane of focus is strongly curved, then the edges will record a very soft image because they are not in correct focus. Similarly, some lenses experience a shift of focus as the aperture changes, which can lead to poor apparent performance at intermediate apertures. The Leica Noctilux f/1.0 50mm lens is notorious for this, for ex&le.
Ultimately there is no substitute for a real-world test of the lens you are using or thinking of buying. This rules out s&le variation and allows you to make some kind of assessment of some of the factors such as bokeh that cannot be easily measured on a bench. Over the years I have found myself choosing lenses based upon the recommendation of people I respect and thorough research of the body of opinion on the internet and in paper publications. I'd love to think that one day all the guesswork could be done away with, but given the complexity of the problem that doesn't seem likely anytime soon.
HTH
-= mike =