Why do the cells of meristematic tissue lack vacuoles?

Quite simply, it’s all down to their job. Meristematic cells are constantly and rapidly dividing to create new growth. A large central vacuole, which is mainly for storage and providing structural support in mature cells, would be a massive hindrance. These active cells need their space for a dense cytoplasm and a prominent nucleus, packed with all the machinery for division. A big, watery vacuole would just get in the way of this vital process.