In addition to this, part of the rationale of the confessional is that the person will have the option of either a face-to-face (if the grate can be opened) and an anonymous confession.Here is what Canon Law has to say on the subject:
Notice it says a “just” cause, which is much easier to justify than a “grave” cause.
On the other hand, it does appear to favor use of some kind of fixed location within the church or oratory and it does specify a grate should be available.
The other benefit of the confessional is that it makes allegations of impropriety against the priest unlikely.
I prefer the confessional. It seems more fitting to the sacrament. Though I do have face-to face sometimes, but only with my SD.