You're missing the point. A number of the codices will be released in a matter of weeks, not a number of years, and GW could easily have posted temporary rules as datasheets for all the units online for free before replacing them with a codex, so the argument about having to pay to play test doesn't hold any water. If GW were truly interested in play testing over profit they would have opted for free rules.
It is rather devious, in my opinion, to release a series of index books, with the implication that they are going to be used for at least a reasonable period of time, only to announce, soon after, that the first codices will be released in the very near future. GW has every right to make money on its products, but this is taking that philosophy too far and I, for one, do not like it.