It's called Jet2.com because, believe it or not, the website address
www.jet2.com generates about 95% of all of the airline's ticket sales. Now, most of us on here would have no trouble finding the jet2 website without it being spelt out to us, but this isn't the case universally. So spelling it out and ramming it home is all part and parcel of a fairly well coordinated approach to marketing.
Nothing to do with the dot.com bubble at all and unlike most of those companies, there's still plenty of people with a few quid in the bank at Channex!!
loco