I don't often raise pet hates here, but here's one.
I was recently told that one of the major causes of accidents at London's termini (and Paddington in particular) was people tripping and falling when walking from an arriving train to the concourse: it seems the scrum to get to the barriers and get home as soon as possible results in people tripping and falling over each other. And the major culprit? Small wheeled suitcases with long handles.
Now, if you've a large case I can see it's perfectly reasonable to use one with wheels and a short handle. And if you have a long way to walk, then it's also quite useful, whatever the size. But it seems to me that the size of the cases with handles is ever decreasing, while the handles themselves are getting longer. As people weave in and out of crowds, they can be hard to spot and form a perfect trip hazard.
The worst offenders seem to specialise in weaving diagonally in and out of the crowd, maximising the chances of bringing someone else down. (I've often thought it would make a good comedy sketch to show ever smaller cases until someone effectively has a purse at the end of a four foot long handle.) It's only a matter of time before someone gets seriously injured.
In the meantime, why can't people carry their cases for the fifty yards or so to the train? Or just buy a small back pack...