Not that it makes it overly complex, but the minimal complexity it adds is pointless.
It's not really though, is it? The point of daylight saving time is that it allows the majority of the population to make better use of daylight. If we stayed on GMT year round, then during the summer, sunrise would be ~0345. Adjusting the clocks forward an hours means more light available in the evenings when more people can make better use of it, rather than 3 hours before they are even awake. Personally that's more valuable to me than being able to forego doing the most basic of mental arithmetic when calculating time zones (and that's coming from someone who is an early riser). Your opinion may differ, and the advantages of DST might not offer much to you, but it's by no means "pointless"
And before you accuse me of being biased against GMT, lighter mornings would actually be great for me. I'm hardly a layabout, usually up and about at 0530 every day, generally earlier in the summer. I like having the world to myself while everyone's still asleep, and I wouldn't even mind if we stuck to one timezone year round, even if meant sacrificing an hour of light in the evenings. But I recognise that most people start their day later, so switching time zones every six months is a compromise that benefits the majority.
Anyway, can someone copy every response in this thread to the forum clipboard, the we can just paste all the same replies again in six months
