There are several reasons to use tape instead of mechanical methods of attachment. The messiness associated with liquid adhesives is avoided, while weight and system cost savings can be realized over channel systems. Further, there is the potential for a reduction in corrosion when using tape instead of flange-mounted systems. And with tape there is no need to punch holes in the sheet metal for pins, which also helps reduce the chance of corrosion introduction.
Additionally, tape allows for more than just attachment; it also seals the backside of the weatherstrip to help block out wind, noise, moisture and dust, when used as part of an overall vehicle noise reduction program.