Probably not a major issue. A lens cap or built-in cover mainly helps protect the lens during transport from fingerprints, smudges, and dirt. It’s less about preserving image quality from tiny marks: minor scratches on the front element usually have little visible effect on photos.

On a camera like the XP140, the lens is recessed, which already reduces the chance of accidental contact. Since it’s a rugged camera meant for wet, dusty, and rough conditions, occasional cleaning is part of normal use anyway. In practice, it usually takes quite a bit of dirt before image quality becomes noticeably affected.

If you store it in a case, that gives additional protection in transit. The main thing is simply to check the lens and wipe it clean when needed, ideally with a soft microfiber cloth. So the lack of a cover is mostly a convenience/design tradeoff, not a serious flaw.