That’s certainly a matter of opinion (and as a German currently living in the UK I disagree): Having separate green light for pedestrians means that the average waiting time is much longer (both for cars and pedestrians) and, further, green light times are often kept much shorter. Having simultaneous green light for parallel car and pedestrian traffic does mean you have to pay more attention, and could theoretically increase the risk of accident (but I’m not convinced that this is the case in practice — in my experience it definitely isn’t!). But on the other hand it means that my time waiting at traffic lights is greatly reduced on average. I thus find the UK system a lot more frustrating.
I actually see the point of the UK system and think it’s entirely defensible. But both systems have their pros and cons.