Birdy, you have raised a touchy issue, as we have had a lot of debate on previous occasions about words that are usually used in a plural form - most notably, pants.
In the past, I've tried to please everybody, and ended, of course, by pleasing nobody.
Chihuahua currently allows both matins and vespers, even though matin and vesper are also allowed, which would seem to lend support to your request. My reasoning regarding these words is that matins is a fairly well-known word, whereas matin (which can be used to mean a morning, or the morning song of birds) is quite rare, so it would seem harsh to eliminate the plural word because of the little-known singular word. The same logic applies to vespers. There is a word vesper, but it's much less common.
The case of lauds seems a little different, because the word laud, meaning to praise, is fairly common. Hence, when the word lauds is used, it's quite likely to mean "praises" rather than the canonical hour, and therefore to be excluded by our rule against verb forms made by adding s.
To admit lauds would probably be opening the floodgates to quite a number of other words, which I would prefer not to do at this stage, but I'd be happy to consider any comments people might make on the question.