Ken:
You came so close to answering your own question!
The lower-end models had the wide-set burners because those were the models farm wives, with their canning and preserving needs, were likeliest to buy. Clustered burners were all very well for ordinary cooking, and looked trendier than wide-set ones, but you needed elbow room for canning.
Back in those days, GE did a lot of farm business; in most rural areas, it was electric or wood-burning, take your pick. Frigidaire was also very well-regarded out in the country. Both companies made high-quality, long-lasting units and backed them up with a service network that covered the nation.