That is perfectly fine, as long as the domain's adhere to google's policies (i.e. non-adult, etc). I bought 5 domains last month that I plan to develop and have them parked with Adsense for Domains until I finish the projects.
It all depends on the niche of the domain and the "type in" traffic it receives. Since they're all undeveloped domains, the most obvious way of them getting traffic is through "type in". One domain is getting some heavy "type in" traffic and has been doing extremely well; the others hardly ever even get 1 or 2 page views, but that's to be expected.