Well, for the clocks, if it is an analog clock, you want to be able to see both hands.
Yes, you are right about that. But you could also have seen both of them it was 03:00, 16:55, 23:15, 01:45 and so on. So why always around 10:10?
I think there are several reasons:
1) It looks like a smile
The clock is smiling to you, happy, inviting you to buy it and take part in it's happy life
2) Put your hands up in the air, put your hands together above your head, raise your hands in joy and happiness for this new clock
Just like the analog clock is doing!
3) 10:10 is a good time of the day, not to late, you can still manage to do all you planned to. And if it's in the evening, well the evening is still young
If it had been 11:55, five minutes to ghost-hour, or judgement-time in five minutes... Better with 10:10