Not quite the same. It's more like, cooking rice takes 20-30 minutes of time and attention (not total attention). A rice cooker turns it into 1 minute of attention (pour in rice, water, wait, remove), but takes about the same time.

So the question is, is it worth it to get in my car and drive 6 blocks, park, and go into the shop, or just walk the 6 blocks? For that distance, it's almost break even on time, but the driving technically requires less effort on my part. Anything less than that, walking is clearly better, anything more than that and driving is clearly better (well, in my case there's nothing after 6 blocks from my place that I'm interested in that isn't at least a mile away so 20+ minutes walking versus 5 minutes driving/parking).

If you use a rice cooker strictly for cooking rice, and don't do it daily, it may not be worth the cost/space.