And lets not forget that in 2016 you're still going to get battered off the line by some little teaspoon sales rep in an 8yr old standard 320d with his aircon on and radio at full volume and 200 sample teaspoons in the boot regardless of whether you have a 3.0 or a 3.2... or a superchip. And he's doing 50mpg plus all day long.
Granted, he's still a loser... but to place importance on the speed of an Omega is rather to miss the point. It isn't "fast" and hasn't been for over 10years.
Sadly I feel my head (if not heart) agreeing with you. When we look at what engine technology has occurred in the last generation of design, it's stratospheric. Up for criticism, of course, but looking just at Post-War, i'd say the generational leaps were something along the lines of automatic chokes, higher compression, fuel injection, turbochargers, cat converters and electronic management followed by various extra emissions junk. But the most recent seems to have combined superchargers, lighter weight, economy, power, torque, emissions, the ruddy lot. 
Ten years ago when I bought my first omega, an ex ARV for £1300 in police racing white, there was nothing I could hope to own for that money that was as quick and fun to drive whilst also being adult car size rather than some boy racer hatchback. 3.0 Manual with LSD. That'll do! And in 2005 it was, or at least seemed to be, one of the quicker moving vehicles on the road.
These days though, as much as I want to like the omega as that car was the first car I really liked, it falls so short when compared to other premium marques of the same era... BMW, Mercedes even Volvo... in terms of comfort and refinement and power. I've had 3 facelifts now, two estates and in their own ways they've annoyed the sh1t out of me. Too noisy... way way to noisy. And bhp/torque for mpg on the auto is apalling. In fact the AR35 is just not good. The merc and bmw autoboxes are far superior for not slipping and just getting on with the job, not to mention knowing which gear to be in.
One day if a nice PFL MV6 manual crops up I might try and relive the magic of my automotive youth but other than that, I think I'm done with Omegas. Definitely auto ones.