Growing up may be hard to do, but it's a lot better than the alternative: slowly rotting away in a room full of stopped clocks. Most obviously, these stopped clocks symbolize Miss Havisham's refusal to, you know, grow up and move on. Let's look at how Pip sees time passing in Miss Havisham's house:
So unchanging was the dull old house, the yellow light in the darkened room, the faded spectre in the chair by the dressing-table glass, that I felt as if the stopping of the clocks had stopped Time in that mysterious place, and, while I and everything else outside it grew older, it stood still. (17.2)
And really, that's exactly what happens. Miss Havisham completely stops noticing the passing of time—but she's not surprised that it happens either. "The days have worn away, have they?" she says (11.46): time is something that happens to other people, and not to her. Pip may have a rough adolescence, but it's better than stopping the clocks.