Re: It's not just SSD speed!
It used to be true that a laptop drive couldn't take that kind of treatment, but most of them today will withstand 100G while operating. But your point that the SSD is more reliable in a more dynamic environment is a good one.
Problem with SSDs taking over the storage world is that there isn't enough FAB capacity to replace all the rotating rust being built out there, at least not for the next 5-10 years (given current growth projections for storage and flash fabs coming on line). Look at the details of the numbers on rotating drives sold; total hard drive sales were around 500 Exabytes in 2015 (http://www.anandtech.com/show/10098/market-views-2015-hard-drive-shipments), with the average disk size increasing from 1TB in 2014 to 1.4 TB in 2015 - with the per-unit cost staying approximately the same. Probably not a huge monetary growth industry, but the growth in storage demand will keep HDDs in the market for quite a while.
Total shipped SSD capacity in 2015 was somewhere around 40 Exabytes (hard to find trustable numbers on this), with the SSD penetration being primarily desktop/laptop (for all the reasons you suggest).
SSDs are getting much greater adoption in enterprise (server) environments these days (density is one of the big reasons; there's talk about 30TB 2.5 inch SSDs before the end of 2017) but there still just isn't the fab capacity to replace rotating drives for all storage yet. Seagate is behind in this particular race to flash, and may be ageing out of the race as a consequence; WDC made a smart move in picking up SanDisk, now to see if they can leverage that to stay ahead of the game. (BTW, Samsung has something over 50% of the SSD market, and virtually none of the rotating disk market; arguably they made the best move to flash of all the HDD manufacturers).