The party that proposed it did well electorally last time too. Apparently there are lots of people in Scotland who vote for the SNP without fully agreeing with their goals.
I'm neutral on the topic of Scottish independence but from a purely tactical perspective it'd be surprising if another referendum could be won at the moment. Sturgeon appears to know that and looks a lot like she's trying to string the SNP base along by claiming to want one without actually getting another referendum.
Problems any new campaign would face:
- The EU. It could be mostly ignored last time. A large part of the SNP base is pro-EU and wants to join as a separate country, whilst another large part of the SNP base is genuinely pro-independence and wants Scotland to be ruled by Scots. These two positions can't be reconciled. EU membership means rule from Brussels. The SNP is theoretically an independence party but would be campaigning on a vision of gaining full independence and then immediately attempting to give it up again, and this would create weaknesses that any competent pro-union campaign would presumably exploit. The hard border and being required to join the Euro would also be a new requirement that wasn't a part of the debate last time.
- Relatedly the financial situation is now worse than before and the EU might not want Scotland as a consequence, as it would be expected to replace the UK's massive subsidies. Joining can take years, in the meantime it would require severe austerity measures to stabilize the new state's finances.
- The SNP has never resolved many of the open issues that caused them to lose last time. What currency would they use, would there be access to the BBC and other infrastructure, border issues, North Sea decomm etc. These questions had clearly been left to the last minute and the pro-union side hammered that fact to great effect. Yet they don't seem to have got much further with the planning since. Tactically this just strengthens the unionist attack line that the SNP don't really want independence - if they did, surely they would be obsessive about all the things they'd do differently after leaving the UK and would have whole libraries devoted to the topic.
If the SNP want to force and win another referendum they need to start having these discussions with their supporters, even if they're unpleasant (e.g. adopting the Euro is generally unpopular).