Part of the appeal of this traditional Russian toy is strongly related to the design principle of repetition. Repetition appeals to us on many sensory levels, especially when the repetition is not perfect, like in nature. The dolls are brightly coloured and you can 'do' things with them, hence their popularity with both young and old.
From little bubby matryoshka with the flower bud through to big mumma matryoshka with roses in full bloom, they never cease to bring back those cherished childhood memories! I don't think our dear little house would really be complete without them!