Some fair points there and I think you could park a lot of these issues squarely at David Cameron's door, he misjudged 2 referendums very badly, came out with all the wrong rhetoric at the wrong time, austerity politics was disastrous, shockingly bad politician playing games for his own political gain. May can only be better.
Brexit is so huge for Scotland and appears horribly misjudged, ill-informed, xenophobic and inward looking that something has to be done even if its just sabre rattling from Holyrood. Scotland does/did well out of EU and needs EU immigrants, feeling is without it UK will never support Scotland like EU does. Feeling is EU doesn't look down its nose at you and tell you to shut-up as the should be deferrent annoying little partner, Scots have a political voice at the moment and powers that be down south dont like it. Despite its faults EU treats all members fairly equally.
Even after Maggie's carnage through former industrial heartlands and poll tax nonsense the nationalist vote only ran at around 20-25% because Labour were strong. They are now going nowhere under Corbyn so look set to stay down in Scotland too and with leaders like Dugdale is it any wonder?
SNP have filled a Labour vacuum, played a canny political game with free this and that for everyone and stood up for Scots, that's undeniable, it is popularism politics and I think they'll get found out at some stage medium term but with their anti Tory rhetoric they'll continue to do well short term and could win Indyref2 should it get called. If May blocked that it will be seen as undemocratic and only drive a bigger wedge in there.
I feel if Labour were still a credible force and led by someone like Tony Blair this wouldn't have ever come about imo - neither Indyref nor Brexit. Not a Blair fan especially and Lefties might not like it but a successful centrist Labour party is essential for the UK to survive I think.
Some very good points here and agree with most of what you say.
if it wasn't for the EU, it would take hours to get to; Tain, Royal Dornoch, even Fortrose