Whilst I can concur with your sentiments you get more investment there than south west Scotland! It is the forgotten part of Scotland.
It is now the largest railway-less area in Scotland and the chances of re-opening Dumfries to Stranraer is zero.
I agree re-opening here is unlikely. But what is the largest railway-less area in Scotland? Without a precise definition that's a tricky question but here's an attempt to come up with some contenders:
Central Dumfries & Galloway
Area Population:
Mid Galloway 11,500
Stewartry 23,500
TOTAL 35,000
Main Towns (2,000+ population):
Castle Douglas 4,000
Newton Stewart 4,000
Dalbeattie 4,000
Kirkcudbright 3,500
Distance of largest town to railway station:
Castle Douglas - Dumfries - 18 miles
Newton Stewart - Barrhill - 18 miles
East Fife
Area Population:
Buckhaven, Methil & Wemyss Villages 18,500
Leven, Kennoway & Largo 18,500
TOTAL 37,000
Main Towns (2,000+ population):
Methil, Leven and Buckhaven 31,000
East Wemyss 2,000
Distance of largest town to railway station:
Methil - Markinch - 6 miles
North East Fife
Area Population:
East Neuk & Landward 12,500
St Andrews 18,500
TOTAL 31,000
Main Towns (2,000+ population):
St Andrews 17,000
Anstruther & Pittenweem 5,000
Crail 2,000
Distance of largest town to railway station:
St Andrews - Leuchars - 5 miles
NE Aberdeenshire
Area Population:
Banff & Buchan 36,500
Buchan 41,500
Formartine 43,000
TOTAL 121,000
Main Towns (2,000+ population):
Peterhead 18,500
Fraserburgh 13,000
Ellon 10,000
Turriff 5,000
Banff 4,000
Macduff 4,000
Oldmeldrum 3,000
Mintlaw 3,000
Balmedie 2,500
Portsoy 2,000
Distance of largest town to railway station:
Peterhead - Dyce - 31 miles
West Aberdeenshire
Area Population:
Dee & Don side (exc Huntly) 30,000
Main Towns (2,000+ population):
Banchory 7500
Aboyne 2500
Alford 2000
Distance of largest town to railway station:
Banchory - Stonehaven - 16 miles
Southern Borders / Eskdale
Area Population:
Teviot & Liddesdale 18,000
Cheviot 18,000
Eskdale 3,500
TOTAL 39,500
Main Towns (2,000+ population):
Hawick 14,000
Kelso 6,000
Jedburgh 4,000
Langholm 2,000
Distance of largest town to railway station:
Hawick - Tweedbank - 17 miles
You could throw in a few other areas like South West Midlothian/Borders (Penicuik & Peebles) or North Angus / East Perthshire (Brechin/Forfar/Blairgowrie) but I don't think they really affect the overall picture.
If you want to strategically connect an area of Scotland that is remote from the railway network and has a large population then everything points at Peterhead being the route you would choose.