It's not the look it's the speed at a maximum speed of 60mph this limits them grossly, there are not many lines they can operate on from start station to destination where they will not cause some sort of pathing issue.
I can think of several lines where a 60 mph limit would not be a major problem e.g.
Llandudno - Blaenau Ffestiniog
Bidston - Wrexham
Preston - Ormskirk
Manchester Victoria - Atherton - Wigan / Kirkby
Colne - Preston - Blackpool South
Lancaster - Morecambe / Heysham
Lancaster - Hellifield / Skipton
Darlington - Bishop Auckland
Darlington - Saltburn
Leeds & Wakefield - Knottingley
Huddersfield - Penistone - Barnsley - Sheffield,
etc., etc.
What they need for such lines is adequate acceleration, not high speed.