Yes, we agree with the installer. We often recommend framed or "semi-frameless" units instead of very small frameless enclosures. There always will be an open joint at the door, and as water bounces off of one's body, it is easier for it to escape out of it if the door seam is right there.

Sometimes this bothers people, sometimes it doesn't. It just depends whether the aesthetic appeal of a frameless shower out-ways a damp floor mat (or the use of a door gasket, which we usually try very hard to avoid).

We should also add that using a rain-style shower head as above does help to reduce this problem, and of course an accurately measured installation!