As the photograph shows the seals around your bath and shower tray are prone to cracking, mould accumulation and general deterioration.
It’s worth checking up on the mastic and renewing it every now and then. Avoid the classic situation: the first time you notice there is a problem is when a drip or a stain appears on your newly painted lounge ceiling which is directly below the en suite!
As a minimum this will need repainting. In worse cases the ceiling (particularly if it’s plasterboard) will warp and become unsightly and/or fragile resulting in the unnecessary expense of having to have all or part of it replaced.