I’ve got you now. It was mentioned in the past but I believe the consensus was that it would be an appalling idea as it would be a huge downgrade for the route as a whole. I believe the phrase was ‘solution looking for a problem’. The Ilkley line is already a fully electrified route with fast modern stock.Perhaps "least-worst" case would have been the better phrase. Simply because as a relatively short branch there's no freight or long-distance traffic to worry about. I only really mentioned it because it seems to be mentioned by those who think "tram-train" is a magic bullet, or those who think the only way to do trams is to find a railway route to convert.
Not sure where the A65 from Guiseley would come into it, as any conversion would probably use tram-trains and not leave the current railway alignment until much closer to Leeds city centre. I did acknowledge that such a plan would be seen as a downgrade, including by myself. If it were to happen the Bradford would probably have to terminate at Guiseley, so that's another reason not to do it. Again, in no way was I suggesting it was a good idea- just that it would be easier (on paper) than any other routes in the area.
Like you I don’t personally understand why almost every tramway/light rail scheme idea has to revolve around old or current rail alignments. It’s feels like someone mentioned the words ‘Tram Train’ and everyone went off and immediately decided that all former railway alignments must immediately be re-opened for this even at the cost of every house, office, factory, school and even hospital that was built over it.