Said that it would be a long one & it is - but it could have been even longer, this is the concise version that ignores a few avenues
Warning: the following includes some conjecture & personal opinion
In the film days Minolta had upto ~25% of the global SLR market making them a major player.
Unfortunately Honeywell claimed that Minolta's AF design transgressed some of their patents & offered to licence use of that IP to Minolta. Minolta's legal representation convinced them that if taken to court they would win so they didn't licence - however, the court didn't agree with Minolta's lawyers & in 1991 Minolta were ordered to pay Honeywell nearly $130million .
That basically wiped out years of camera profits & affected R&D budgets for new products.
You may be interested to know that Minolta introduced their first DSLR in 1995, the same year that Canon introduced theirs
It then launched a follow up in 1998 but subsequently decided that technology was changing so fast & at the time the market was so small that it couldn't recover development costs before bodies became obsolete.
It didn't re-enter the DSLR market until 2004 (albeit now badged as Konica Minolta) with what actually were great cameras (the 7D is still probably the best DSLR in terms of ergonomics - lots of knobs etc. instead of menus) but were probably a year too late (probably due to the events of the next sentence).
Like Canon, Minolta's business machines division was a more important part of the company than optics & Konica was in a similar position & also had other complementary products (film, processing labs etc.).
Konica & Minolta agreed to merge hoping to take advantage of synergies, volumes of scale etc. & did so in 2003.
A few years later it turned out that Sony had been looking to enter the DSLR market, had decided to licence a mount rather than develop their own from scratch & had been in discussion with various companies (it's known that they considered buying Nikon lock, stock & barrel) .
KM & Sony agreed a licence deal with the intention of them both producing competing lines but sharing the same mount. It's believed that slightly later KM came to the conclusion that in the future the digital camera market would come to be dominated by electronics companies (e.g. Sony, Panasonic, Samsung etc.) rather than optics companies* & decided to concentrate on it's other areas.
After further discussion with Sony they came to an agreement for Sony to effectively buy out KM's DSLR assets & licence some IP (KM apparently retains the right to re-enter the market if they wish & they still make lenses for e.g. JVC camcorders).
As for changing the name of the mount it's possibly Sony hubris but it's much more likely that as KM still exists as a large global corporation Sony simply isn't allowed to use Konica Minolta trademarks.
The first Sony DSLRs (A100, A700 & A200) were obviously heavily influenced by Minolta's heritage & are excellent cameras for their market sectors.
From there on there is obviously more internal Sony influence - e.g. for long enough I've believed that the A230/A330/A350 series were an attempt to basically produce a "bridge" camera but with an interchangeable mount.
Whether they were uncomfortable because of their small size (which also compromised battery size) or people just didn't expect a DSLR to be that small many people considered them as a backward step & Sony realising it's error moved quite quickly to replace them.
Also, Sony as a consumer electronics company was already used to annual product refreshes - unlike the traditional camera companies. Similarly multiple SKUs with only minor differences is a consumer electronics marketing approach.
The A900 again showed a lot of Minolta heritage being similar to an A700 but with a larger viewfinder & the same sensor as the Nikon D3X (the processing is different though with, I believe, Sony using on-die processing but Nikon opting to process off-sensor - part of the reason for the price difference)+.
The A850 I have on good authority was launched at the express wish of Sony USA to get to the $2000 pricepoint for a FF.
Similarly, I have it on good authority that at least in Europe the dearer A900 outsold the A850.
Nor have Sony forgotten FF & if, as expected, they launch another FF body this summer it won't have been any slower than Nikon's FF body replacement programme & only marginally longer than Canon's.
Despite having markedly increased Minolta-AF/Alpha mount DSLR market share imo Sony appear to have come to the conclusion that whilst they could gain market share that it would take many years to achieve parity with Canon & Nikon playing the "me-too" game & also possibly that by the time that they achieved it that with technological advance the market would have changed anyway*. Hence we have different technologies from them like "Quick AF Live View" & SLT which to be fair do have some advantages as well as some disadvantages.
& if you can charge the same it's simpler & more profitable to build with an EVF than an OVF especially if you make your own EVFs. Sony are excellent at production engineering & parts sharing.
Sony have shown many times over their history that they are willing to innovate - it doesn't always work but when it does it leads to large enough profits to pay for the failed attempts.
Canon (& I say this having worked for them many moons ago) is more of a "safer" company but with an exceptional marketing department.
Here endeth the lesson.
* & imo they were right
+Also, there does appear to be some collusion between Nikon & Sony on sensors even if it's only cross-licencing of IP.