GhislainG :
I presume you're not in IT, otherwise your perception would probably be different. The role of IT often is to provide solutions to make a business more competitive.
That depends on what you're doing...if you're typing documents and using web browsers...where do you gain from buying a more expensive system, when one far simpler would do the job?
With virtualization systems, you still wouldn't see a dramatic performance increase that justifies the increased cost of this generation.
Additionally, if your workloads are heavy, then 4th gen intel's have terrible power consumption numbers compared to Ivy Bridge at anything above idle.
The only time I could even see someone argue the case would be if your system was going to run at idle over 90% of the time when it's on during the day. Otherwise increased initial cost + increased power consumption does not justify a 5% performance increase for jumping to a new hardware generation.
Value over performance...as a business, I can justify 10% higher costs and 10% higher power consumption for a 30% performance increase. I cannot justify it for a 5% performance increase. In this instance total value < cost of new hardware.
It's not justifiable...clearly you've never run a business, or your perception would be different.