I'd like to see this tried in another of the franchise users first. Not withstanding it does look interesting. Although I'm not in favour of reducing the show to one night, app voting could well help that easily if it was needed by the BBC. Melfest has shown how it could be demonstrated on screen too. I think 'votegate' is still sufficiently current in memory though in broadcaster and regulators minds to even now prohibit app use.
App voting is used in the UK by the ITV shows alongside phone voting.
Melfest gets a lot of complaints re the results it generates.
Because people like yourself have nothing better to do than complain.
I do agree Strictly isn't the sort of show to lead with this sort of thing - it would probably be more logical for Dancing on Ice to get in there first considering they already have app voting in play (I don't think the BBC even have a Strictly app, certainly not for voting, though you can vote online). It would also need testing before going live for an entire series - they could do it for a year as "just for fun" just to see where abouts the scores are landing. I was thinking you get an average score, round it up to the nearest .25 then multiply by 4 to get a score that balances the judges, but if the viewers are harsh enough that a score in the high 30s isn't likely they might need to stick to the ranking system.
I preferred the internet when it had a sense of humour.