Why no 5400 RPM 2.5" drives with 32+ MB cache?

It is no secret that the market for HDDs is being substantially altered by SSDs, with their price dropping every week. Many SSDs saturate SATA III and the next big thing is a PCIe SSD which can take advantage of greater bandwidth. This is causing a shift in sales away from HDDs to the consternation of WDC employees. WDC and the other vendors are naturally moving toward hybrid drives to take advantage of the shift.

That said, one of WDC’s practices makes no sense. Virtually all 2.5" 5400 RPM HDDs only have 8 MB of cache. Seagate is the only exception with a few drives containing 16 MB of cache. The only way to increase the performance of a 5400 RPM drive is to increase the amount of cache, so why doesn’t WDC offer 5400 RPM laptop drives with 32 or even 64 MB of cache given that the engineering investment would be rather small?

I believe that the market for these drives would continue for some time, as 5400 RPM drives are energy efficient, though they would need to be priced accordingly. Some customers would use these drives in existing laptops, with others using them in external USB 3.0 (now 3.1) enclosures for backups or to increase the amount of data storage in laptops where reinstalling the OS to take advantage of a larger, faster drive is problematic. Hybrid drives are faster, to be sure, but they are also much more expensive. Would these drives occupy the lion’s share of WDC’s future sales? Of course not, but right now WDC is ceding the market to Seagate, with Toshiba also gaining due to its low prices.