I agree this is a big job. Overhauling an existing application means a ton of work for both the designer and the developer. However the primary goal of designers should be making users work effectively. Building something that also looks good is a secondary goal. Great designers achieve both goals. If skills or budget are not great, go for the primary.

In the case of Audacity, I remember that I have to google how to silence a selection every time I get back to it after a break of several months. I guess this means that the primary goal is somewhat missed.