The Magicard was aimed to computer and electronic hobbyists who also happened to own an Atari 2600, it wasn't a product for the general video game console market.
In fact it was advertised in magazines like "Popular Electronics" or "Byte"
People buying this were interested in its functionality and in the included manual, not the packaging. They were building electronics projects published in magazines and buying kits (The MagiCard requires to build an additional circuit for the cassette interface to load and save programs and provides schematics and theory of operation for such interface in the manual).
The presence of a case and label was totally irrelevant, and a fancy artwork wouldn't have had the effect of making it look more "professional", but exactly the opposite. It wasn't a toy, and shouldn't have looked like one.
The Magicard allowed to inexpensively turn a 2600 console into an hobby computer similar to some of the single-board computers like the KIM-1, at least in their basic configurations (BTW, a professional product. No case or label, just a bare board and docs).
Moreover, its manual was an invaluable source of information for everyone who wanted to write commercial 2600 games.
Check this post by Dan Oliver, for example
At that time I know companies were willing to buy stolen 2600 programming manuals for hundreds of thousands of dollars. But then Magicard comes out for $50 with what turned out to be a complete 2600 programming manual. I think every company that started making 2600 games at the time bought one copy of Magicard.
And this unclassified Ad from "Byte" magazine 04-1983:
Video Life is a much more niche product than MagiCard (which already is a niche product!). It is something that would mostly interests mathematicians, and it was more interesting to program it on a computer (A reduced version could be coded on the Magicard, and it was in fact one of the example programs on the manual) than having it on a cartridge without the ability to modify the code.
I find reasonable and expected that its sales were just a (very) small fraction compared to Magicard.
MagiCard and VideoLife used the exact same pcb and parts. Just the code programmed in the eprom differs between the two. I see Video Life was a way to help selling the existing MagiCard parts, and it made sense producing it only because it didn't required investments for new hardware.