Mainly as Movistar have around half the budget of Sky if those figures that came out in July are accurate, and they seldom make big marquee signings. They don't represent a wholesale change in the sport because they've been in existence, doing business the same way, for over 35 years, being one of the top teams for the majority of those. Sky are, rightly or wrongly, perceived in the way that, say, Manchester City are - that the success is bought rather than built. This is even the case despite riders like Froome who've clearly become stronger riders since being there and some riders being bought as prospects (such as Henao and Moscon). When was the last time Abarcá made a marquee signing that matches the kind of scale of the Landa or Kwiatkowski signings? Cobo probably? That's five years ago. And even then, he'd been there before and it was more off waivers than anything else due to pressure to have the Vuelta winner on a Spanish team. Before that, Visconti who'd been previously at a ProConti team he'd clearly outgrown. Abarcá do a lot of frustrating things - overly molly-coddling riders, paying over the odds on clearly over the hill mountain helpers (Gadret, Szmyd, Moreau, Bruseghin), re-signing riders they've previously had (Moreno, Plaza, Costa, Valverde) or taking flyers on riders whose careers are regressing (Antón, Rujano, Betancur), but just throwing the chequebook at big names to fill out their roster is not an accusation you can realistically level at them.
In fairness to them, most of Sky's biggest names were not bought as big stars, and those riders who were have often been the ones to have stagnated or regressed at Sky - Lövkvist, Boasson Hagen et al.. But the fact that they have bought a bunch of riders who had been interesting stagehunters and added to the entertainment value of races, and promptly set them to work doing the exact opposite, does breed resentment, and understandably so. Going to Sky may be beneficial to Kenny's bank balance, and may improve his skills as a rider, which is good for him. I have my doubts, much as was detailed in somebody else's post earlier - he goes from being an interesting stagehunter and secondary classification candidate in a team that gives him freedom to just another domestique in a team where he'll be about 23rd in the priorities list, nestled between the guy responsible for the mood lighting and the guy paid to delete stupid things Peter Kennaugh says on social media. However, we as fans watch this sport as it entertains us, and seeing somebody who entertains us making a move that makes it likely that he will not be doing that going forward, is a reason for the negativity with which this apparent transfer is being greeted.
It is like a stylish and skilled but not elite footballer who could be a great playmaker for a mid-table team signing for a Manchester City or a Real Madrid - they'll do a good job when they come on, and they'll get a good contract, but mostly they'll sit on the bench for a couple of years because those teams have superstars in the same kind of role he can command.