There are other enhancements such as SSE4 instructions, larger cache sizes, runs cooler, uses less power and does more work per clock cycle compared to a 65nm part.
If you've got a 65nm processor and it's doing the job for you then of course there's no need to upgrade. But for people who have something a bit slower or who want to OC to 4+ Ghz then this is the puppy for them.
You seem to think Intel just overclocks old parts to make new ones. It's not at all like that. Penryn isn't simply an OC'ed shrunk down Conroe as you're suggesting.....
Whether an upgrade is worth it is up to the individual. I have a 36gb raptor which is nearly 5 years old now and although there are faster drives out there they don't justify the expense for me to upgrade but if you were building a new PC or upgrading one that wasn't quite so good then a 150gb raptor might be worth it for you.
Some people like myself think of the future when they build a PC. Rather than buying an E6600 for close to £200 when I built this PC I chose to get an E4300 for about 70 and when the E8400 launches I'll get that for the new PC that I'm building. At the end of the day if I'd bought the E6600 I'd have spent the same amount on CPU's and still only had one PC. Now we have two and I'll get better performance.