Personal preference
One can be just as comfortable and efficient paddling with straight legs as with bent legs, if one is used to the position. Greenlanders have been doing it for thousands of years and it’s common among Greenland-style enthusiasts today. In fact, a properly fitted skin boat requires straight legs.
padding out
I believe Celia made the point that her legs found the right position with padding out her thigh braces. I have a p & h quest that with a cockpit that was much too large for me. To make it fit, I installed minicel custom braces and then glassed them in dropping the stock braces about 4-5 inches. My feet are now at 45 degree angle to a slightly slopped minicell footrest. My legs are slightly bent and rest comfortably in a natural position. Pressing slightly on the footrest brings my thigh (skinny) up into the thigh brace for bracing or allows my knee to drop with backward rotation of my sameside hip to facilitate the forward stroke. Most folks I see who are uncomfortable have jammed themselves into a boat that doesn’t fit properly. You can’t paddle properly in a locked position–leg/hip movement is critical to letting the boat move under you in conditions, for a flexible and powerful forward stroke, and for bracing and rolling. So, when I get a new boat padding it out is task one–I find that it usually takes a few paddles to dial in the correct modifications, many of which are done on the water with a dragon skin tool. This is the only way only way I know to make sure that the legs/feet rest naturally in a relaxed comfortable position that still permits the natural leg motion required for the forward stroke (onside leg drops and hip rotates back) and bracing (onside leg rises into thigh brace) without having to think about it. The latter is key: if you have to think about it, your boat doesn’t fit you.
most kayaks are not Greenland style
but if you prefer that type of paddling that is great.