Dear ERose,
I live in Thailand and to find monasteries which do not ordain temporarily (boys and men alike) is, in my experience, rarely found, it is an integral aspect of the culture, similar things hold true for Myanmar. In most of the cases I came across personally, I found it rather uninspiring to witness the status quo as it comes to temporary ordination, especially regarding young boys.
Actually I would see a lot of potential in the development of good qualities with the aid of the practice of temporary ordination if the guidance the youngsters receive would be proper and if they would have at least some inclination to do it and are not entirely forced, which I think would not be approved by the Buddha. In most cases the people (boys and men) do not truly value core aspects of monastic life and often do not behave at all like monastics, are rather happy if the whole procedure is over or completely live essentially indistinctly from householders or their offspring.
So in monasteries which have very low standards as to dhamma and vinaya we often find scenes of little sāmaneras who play video games, football and follow other activities of a similar kind. In such cases they do not suffer much since this approach is by and large not at variance with their lives outside the monastery. In monasteries where the standard is more strict, as in my place, the young men find the effort of the training in many cases rather burdensome which is easily observable in their inclinations for chatter and a general dissatisfaction in their appearance, though they are curbed from any gross behavior not becoming for a monastic (such as the examples given above).
Nevertheless I was positively surprised at how well behaved they were, after having put off the robes and therefore now markedly more relaxed, towards monks and how descent an effect it had on connecting them with the monastery and the religion.
I can remember some examples in the canon where the Buddha or the other monks seemingly allowed or even used it as a skillful device for keeping people on the right track, to lead them into the saṅgha or keep them in it by turning to wordly means and incentives (ven. Nanda might perhaps serve here as one example, whom the Buddha kept in the brahmacariya by promising him divine maidens). From that point of view it might be considered wholesome to allow temporary ordination in some cases, bearing in mind the positive effects it can have on the individual.
Another thing maybe relevant too, at least to some extant. The Buddha made it a prohibition to not ordain during the vassa period people who wanted to because these individuals changed their minds after all and did not ordain at the end. I remember also cases of ordinands who initially did not wish to go forth (Ajahn Mahā Bua is a famous example but even one monk staying with me here) and who decided to stay in robes successfully in the end. The point I want to make is that the staying in robes as such can have a conducive overall result.
To sum up I would deem it therefore perhaps proper to perform such ordinations as long as there is adequate guidance and teaching as well as a certain amount of separation of the ones who want to devote themselves to silence and more intense practice and the ones who have to struggle in other areas and live this live governed by other motivations. In places where these principals of guidance etc. are missing I see at least some benefits, as it comes to the provision of education for the young and having at least some connexion to the religion, how corrupted it may be. These are some of the main points I see to it and which I would like to offer.
Blessings
because meditation and quietude proofs very beneficial for the brain.