Tech industry analyst Paolo Pescatore said while Amazon's move may frustrate owners of models which still work, the decision was "understandable from a security and support perspective".
"The challenge is that these devices were built for a different era and are not equipped to run newer, more data-hungry services and features," he told the BBC, adding "ageing hardware" can also pose problems.
But Pescatore said older devices losing the ability to connect to newer products and services can also "turn a once seamless device into a far more limited offline tool".
Ugo Vallauri, co-director of the Restart Project, which encourages repair of electronics, said manufacturers' promises of newer devices offering better performance, when ceasing support for older products, has been seen before.
"However, that's hardly a good reason for soft-bricking millions of still functioning devices."
Vallauri added while the company has said the change would only affect 3% of current users, "this could amount to 2 million devices rendered obsolete according to some estimates, potentially generating over 624 tons of e-waste".
Additional reporting by James Kelly