I agree with you about not letting properties get into such a bad state in the first place, as this costs more in the end. We had this issue with Lewisham Homes on a leasehold flat, the roof needed repairs and tiles replacing but despite our constant nagging the repairs were never done properly, the roof leaked and in the end the whole roof had to be redone. I think this could have been avoided if it had been maintained.
When we moved into a freehold property, one of the first things we got done was to get a reliable roofer round to replace loose tiles, fix gutters etc. This was instead of buying furniture or decorating, because we knew that in the long run this would save us money. Unfortunately as you say as leaseholders don't have this choice and end up paying for bad management.