Even so, those drives are still painfully slow for those tasks.
I've replaced those 5400rpm drives with SSDs on two MBPs in the past month. The users of those computers couldn't be happier with the resulting speed increase.
If you'd replaced those 5400rpm drives with 7200rpm, would they have noticed as substantial an improvement? Nobody here would deny the benefits of SSD. SSD over spinner, SSD over Fusion, SSD over 5.25" single-sided, single-density floppies, SSD over punch cards...
SSD is not some sort of religion, where all non-believers must be converted. The benefits are obvious, and so are the costs. And as anything else on a cost/benefit graph, at some point, price trumps performance. The day may come when SSD and HDD reach cost-per-byte parity, but considering the way HDD makers keep boosting the capacity of drives while maintaining unit price, it may still be a while.
The weight and size advantages that make solid state storage so nice for laptops is less critical in desktops, and the lure of "massive" internal storage still exists for many buyers. Fusion does a good enough job of bridging the performance gap (for most users) that it's likely to last longer than some people think.