You’re right, 15 years ago I did basically exactly this!
The reasons were similar – I wanted the look of the RS kit on the Mondeo, but I wanted the 2 litre engine and the Ghia X trim. The RS kit was only available as a Zetec-S with the 2 litre engine – the Ghia X models with it were rare and all V6, which was uninsurable at 19 anyway. But the Zetec-S was very poor spec, cloth seats, no cruise, etc.
So I got a Ghia X and bought a used set of bumpers and skirts off an ST24. It was already in the right colour – I fitted the skirts myself, had the rear bumper fitted when I had the exhaust moved from one side to the other (the outlet was the wrong side) and the front bumper I had resprayed and fitted by a bodyshop.
The result was a car with the spec I wanted which looked great and I thoroughly enjoyed owning, cleaning and looking after in a way I just wouldn’t have had it looked like a plain Mk2. I got a good deal on the parts – 200 quid off a guy fitting some bizarre bodykit to his 3 year old ST24 – and probably paid another 300 quid or so for paint, exhaust and fitting.
Don’t see fitting OEM parts to cars to improve the look as ‘chav’ at all – its just part of the car hobby, isn’t it?