So now that you know how easy it is to learn to program for webos (html / css/ js) - would the # of users it takes to make the ROI be reduced by enough such that it's ok to sell to an extremely small market?

ie. Since it's so easy to develop for, you will spend very little time/effort/money to learn to develop vs the iphone (which involves apis, objective c, etc) or vs the android (which involves java, etc) - and so it's ok that the market is small, because you can sell less copies to recoup the investment outlay (which was smaller to begin with because of the ease of development).

Does that change the value proposition of the touchpad?

If it does, then this points to a marketing failure on HP's part - they had a perfectly fine product - just needed to get past the initial "knowledge gap" when no one knows anything about the product.