If AMD would want to reset their brand perception, the best way for that is to give a killer offer, like one you mentioned. There is a lot of reasons why AMD would do this. If Zen will be on Haswell level clock for clock, then next generation CPUs will only be better and that is potential for not only turning the tide on CPU market, but also growth for AMD. But for that they would require changing the perception of their brand.
What is a better way for the "mindshare brand reset" than offering solid hardware at a bargain?
Think about this. 6 core Haswell-E for 250$(SR5), with GTX 1080(Vega 11) for 500$. Would you not buy something like this?