Similar to attic areas, crawlspaces are often out of sight, out of mind. Problems may have developed or worsened over time and you are finally starting to notice the effects inside or above the house, such as sagging floors, odours, or cold floors. The issues might be structural, moisture, pest/vermin, or insulation related.
If you know something is wrong, the longer you wait to address it, the worse it may become and thus more costly to rectify – have the area inspected so you know what needs to be done and can plan accordingly.