I found few bits that I do agree, but in general, that article is just plain wrong.
STI was never about the speed. It was always about rallying, and in FIA rallying, there always(since group B was banned) was limitation on HP engines could produce. And thats what these cars were built for, being reliable on that HP and having the best handling characteristics possible.
Giving the STI model more HP means, they cannot compete in WRC(which they aint in years anyways for tons of reasons) but at least they are still competing in rally america etc.
Yes, sure, faster STI from factory would be nice, but why? Ppl buying STI knows that they can and will mod them, they are buying them because they are like LEGO. Sure I could go ahead and buy 50-80k pounds 500hp car, but thats not what subaru owners ever wanted. Subaru owners always wanted to buy that piece of LEGO.
Subaru as company knows exactly what their long term customers wants and needs, thats why their numbers are growing every year, as they are getting more and more happy always returning customers(this unfortunatelly doesnt apply in EU, mainly Ireland, because of stupid EUR limitations and taxes).
To completely shred that article in pieces, lets have a look at the successes of the new STI
Rally of america - winning one race after another, yes David Higgins is a beast, and he knows what hes doing, but the car allows him to push even further
Nurburgring 24h endurance - sweet 19th place, beating cars like Nissan GTR, Carreras, and buch of others GT3 cars... I mean, cmon, really does STI need more than 300hp?