Amongst the many reasons I dropped my ambition to be an MP (along with a drubbing at the hands of a truly charismatic politician in 2001) is that I realised I actually wouldn’t be very good at it. I can’t think of any other career where sticking to a path when you realise it is the wrong one is actually seen as a strength.
I think U-turns are seen as wrong because it suggests you lack the courage of your convictions. To update the language, it’s about ‘vision’ and ‘mission’. A party will rarely change it’s overall vision for the type of country they want to create, party politics would be fairly pointless if they did because you need to have some bedrock of principle for a party to function.
However, they might change their mission, the way they think they can best get there. Like you, I don’t see a problem with that; times change, technology advances and priorities adapt.