Tim Cook ruined Apple. Apple is a product company, it need more revolutionary product to survive. I agree that Tim Cook make Apple the most profitable company, but that doesn’t last long if there aren’t more revolutionary product being launched.
To hear some people talk and that includes plenty on the forums of this site, Apple doesn't need more revolutionary product -- although who's not interested in seeing what the next "one more thing" will be?-- it mostly needs to pay more attention to QA, bug fixes, user feedback on existing product (hardware and software). All this is a natural outgrowth of having become a major vendor of attractive products on a volume basis they may have only dreamed of back in the 80s.
And not everyone fancies himself an annual updater of computing gear. "Some people"

like me buy groceries every month but we may spring for a new-to-us car or an Apple-refurb computer only when the other one flat out dies.... even if we are part of the Apple aficionado crowd that did stand in line for a first gen iPhone, and then maybe a 4S, and maybe an SE... get it?
This is why companies have marketing departments. To gather in new customers and keep the repeat ones coming back
when they can afford it.
Oh but then it really is a fact that there are also the "
but is it revolutionary?" junkies... who imo are busy making the computing gear industry into the next fricken "fast fashion" catastrophe that has befallen the garment industry and the planet. That's been the case ever since the owners of capital in a consumerist world they created to enrich them realized that you have to try to make people buy more and more often if they have become part of the bottom 80% of the planet that can't buy quality goods because they don't make quality paychecks. But responsible managers of capital try to manage business in a sustainable way.
Tim Cook hasn't ruined Apple. Tim Cook has pushed to make Apple stellar in safeguarding user privacy, get greener -- use more renewables, provide paths to recycling-- while offering innovative gear for users along with services to complement and enhance them, at a range of prices and now including pricing and products suitable to a burgeoning Chinese middle class. And let's not forget all that included software including impressive OS and iOS releases with ipad OS upcoming. Is Apple stuff pricey? Oh, maybe we forgot about the OS and the included apps and their interface with the company's services and stores.
Are those things perfect? Hell no. Could Apple do better? Sure. They're working on it, since they want to stay in business. CEOs get paid to look down the road five years out, day after day, and hazard a best guesstimate today on what it should be doing at that essentially unforeseeable point. Cook made CEO in 2011. So far it seems to me his assessors (the markets, the customers) seem to think on balance he's got pretty good eyesight. We wanted portability from our gear and still score that high as a priority Apple gives us that. We wanted privacy and Tim Cook said hell yeah and we got that too. Some of us have started wanting more focus on environmental and social/economic justice issues and Apple's been relentless in trying to get there without damaging its own bottom line.
None of this stuff is simple. All of it matters. Apple's board of directors is a diverse lot with diverse connections and they seem to think he's getting the job done. It's not that we in the peanut gallery don't count. We do. But most of the gallery must still be giving Cook a thumbs-up or he'd have been gone already because the board of directors (and Wall Street) hears us loud and clear too. Not least through our purchases and as repeat customers.
Dear Tim: Thanks! (and now about those bug fixes and that attention to user feedback...)