In addition to the issue of not wanting to float over the runway when a crosswind is blowing you off it, for those who use the side slip method of crosswind landing, there's the whole Cessna "slips with flaps" issue.
Whether it's a forward slip or a side slip, the C172 elevator can lose authority in a slip with flaps. Later models are placarded that slip with flaps are not recommended. They are not prohibited.
Also, your rate of descent is higher in a sideslip than a straight descent, so for the same headwind component you'll have a steeper approach path in the sideslip. Adding full flaps steepens that approach even more.