Translation Pricing by the Word or Hour?

Recently we read another translation blog that suggested paying translators by the hour rather than by the word. Hourly compensation would:

1) Mean that the longer a translation project takes the more a translator makes.

2) Disincentivize translators’ investment in translation technologies, which have some cost, to encourage more efficient and consistent translation work.

3) Make it more difficult for translation clients to budget and plan for firm costs associated with translation services.

These are just the first three things that come quickly to mind. Why is the hourly compensation model not the translation industry standard or gaining momentum? Please refer to points 1-3 above for starters.