It just seemed like a good compromise between getting the content and spending all of the transponder space.
The principle argument against VOOM channels is repetitive content and their relative worth versus other content for the same transponder space. The principle argument for VOOM channels was that some of the content was compelling enough to be seen. This would put the onus on people that want the content (and have the bandwidth to get it) but would give DIRECTV the benefit of making it available.
I have a 5 Mbps connection at home and have really gotten a lot out of the current VOD SD content. Yes, HD VOD would be slower, I know. But think of it this way: VOOM has 5 shows you'd watch per month. You could queue them up and watch them whenever you wanted. The download times won't be fast, but it is faster than not having the content at all.
The other viable option would be a DVR-friendly channel with single runs of all the month's content across all channels. Imagine a channel with blocks of content from all VOOM channels looped. It only takes the space of one channel but is geared specifically for timeshifted viewing. Each piece of content is shown once a month on the combined channel. Perhaps new content is shown once a week.