The trouble is, what significant settlements does that put back on the railway map? Market Weighton, and possibly Holme on Spalding Moor and Middleton on the Wolds - and where does it connect them to? Driffield and Selby. I can't see that that would ever wash its face.
Looks to me that the line has got potential, and stands up very well with many of the other lines on the list. It will:
1. Aside from the places that you mention, also serves Bainton, Foggathope and Bubwith, all ripe for development. I am assuming that the smaller former stations would not be re-opened.
2. facilitate the development of Filey, Bridlington and Driffield as commuter areas of Leeds (by through trains), potentially improving their economic fortunes.
3. facilitate tourism from Leeds/West Yorkshire to Bridlington and Filey (by through trains), currently a tortuous journey by rail.
4. provide a diversionary route when the direct line from Hull to Driffield via Beverley is not available.
5. improve links from this part of East Yorkshire to the wider country, by extending/diverting Cross-Country services from Leeds to Bridlington.
6. 'Fill in' a section of the railway map so cruelly removed in 1965.
7. Be easy to electrify as few overhead obstructions or limited clearances.
I think the line is relatively unobstructed by development (apart from in Market Weighton, where a deviation may be required), and there are not lots of main roads to be crossed or urban areas to be traversed.
30 miles @ £20m per mile = £600m.