"As you can see, there aren't many reasons to buy traditional magnetic disk"
Hmm, you give a list of arguments for buying traditional hard disks and then say there aren't many reasons?
"SSDs are faster. They have way lower latency. They consume less power. They take up less space.
Most importantly, so long as you follow the instructions on the tin when selecting the right SSD for the job, there is absolutely no reason not to buy one"
Apart from the main one of price and/or price per GB? If I want a 48TB SAN then filling it with enterprise SSDs is going to cost me significantly more than HDDs!