" As far as I can see, the point to doing the experiment was to demonstrate that changing environment can change physical structures without needing mutation to cause the change."


Bettynh- I see why you say this, but upon going to the researcher's site we see:

"Standen's team said that if some ancient fish adapted this way, the pressures of evolution would select the most successful for life on land.

"Potentially an ancestor (to modern land animals) had that same plasticity, which allowed it to engage in new environments," she said.

A couple of years is indeed not a direct demonstration of evolution, but of observable traits that are similar to indications in certain fossil records. We can't, as the relatively short article notes, "view the behavior" of very old fossils, but we can see HOW such things might happen.