As I mentioned earlier, the move to semiannual release schedule was expected for some time because the speed of development in tablets, the hottest personal computing field, is becoming very fast, resembling early years of PC development.
Apple learned a very valuable lesson from those days.
In early PC years, Apple was aiming for profit and neglected the market share. It resulted in situation, when Macs were cream of PCs, but expensive and lost market share enabled Microsoft to dictate marker later, a mistake made partially by Sculley based on usual business philosophy and lack of understanding of the new (then) PC market.
When Jobs returned, Mac was in ruins and there was nothing left to fight for. He made peace with Microsoft, negotiated terms of GUI license with Microsoft and move on, to the next concept of Mac as a digital entertainment hub. He never forgot however the lesson of lost market share and did everything possible to fight it (yet not losing profits either). In this process, Apple fully took control of the cream of the market - ultraportables and notebooks and also PC stations/servers (which is what Mac Pro is) and also consumer segment - iMacs, leaving assembled grey boxes to likes of Dell and HP to fight and die for.
Moving to digital hub concept, Apple fully took under control digital music market, created one of largest online stores in the world - iTunes, conquered mp3 market to extent even now rarely one thinks of other mp3 players (though there are plenty), crushed Sony in the process. Movies, music videos, books, games - in all segments iTunes or Apple Stores are one of leading, if bot the leading distributor.
Next move was to take under control smartphones, which again Apple did successfully, crushing likes of RIM, Windows Mobile and Palm in the process. Annual iPhone releases went well because of contract nature of smartphone selling, tied to carriers. This model doesn't work that well if there are no carrier subsidies (i.e. for developing countries). Since people in those places so far mostly used feature phones and only now beginning to shift to smartphones, this is time for strike. While there is a talk of lot of Android stuff in developing countries, most of the phones are of very poor quality, cheaply made and pale in comparison with iPhones. Make no mistake - those people would love to buy iPhones if they could afford, hence you can see in China a LOT of fake iPhones, giving their owners a prestige they desire at very low prices.
Similarly, whether you like it or not, in tablets despite the existence of earlier Windows tablets, iPad was and still is a category defining leader and a trend setter. There are many Android and Windows tablets there, but nothing come close to seamless integration of software and hardware done by Apple.
Having said that, once the categories are set and consumer tastes clear, the usual rules of free market kick in and a lot of competitors are entering. They usually try to diversity themselves either by very low price (think Nexus 7, Kindle Fires) or by something that iPhone or iPad don't have - huge 5 inch screens (Galaxy and others), stylus (Samsung Note series). In a case, Android offering is not very different from Apple (Samsung tablets) in terms of size or prices or even design, consumers prefer Apple offering. So, every manufacturer out there is either offering a low price or different feature set options, which is what competitors are supposed to do. Since there is a myriad of such devices, its inevitable the Apple market share will decrease.
The most valuable lesson for Apple which Jobs learned, was that you cannot stick to highest priced segment and reap profits and neglect the low cost.
So now its a stage when instead of offering highest or one of highest number of app in App Store, its a now stage when you have to fight for market share.
The first move in tablets was iPad mini, which is only a first step of offering different size, different price (lower) iPads. While we don't know the quarter results, all the preliminary stages show it was a very successful launch - not only in terms of sales but also in diverting mini tablet sales to Apple from Google or Amazon.
iPhone mini is also a right step in that direction.