Another option is more efficient coding in software development to reduce the number of IOPS.
The best example I can think of is Google. Hard to believe, they use consumer grade hard disks in their servers, yet are well capable of keeping up with the billions of search requests across the vast database it indexes.
On the other hand, for large businesses that use inefficient disk intensive software, it generally would be quicker and cheaper to replace the HDDs in their servers with these SSDs than spend months improving and testing software to achieve similar results with their existing hard disks.
This is why making shortcuts in software development can come at a cost later on, either in more intensive RAM usage and disk usage. Some examples include Windows Vista and Norton Internet Security suites leading up to 2008.