For a couple of clients, notably MarkMonitor and Exigen Information Systems(EIS), I created alternate cascading stylesheets (CSS) to visually bring large parts of circa 2001/2 web apps to feel up to date and match new features without touching any working code.
Snap of live site, not figma / photoshop
When asked about how design matters, entrepreneurs and sales (GTM) tell me its about perception. Imagine soldiers on parade or crown molding in a show house. A tidy, consistent, current, and inoffensive visual language speaks to tidy, consistent, competent set of engineering underneath. Even if its a lie. Especially if you need time to make code that lives up to the polish.
Now armies don’t fight like they parade. House buyers don’t pay for good insulation or careful plumbing: they can’t see hidden insulation or careful construction the way they see visible crown molding. Look + feel creates a story for buyers about the underlying quality they can’t see. Ask any software engineer whose worked on some product admired by users and you will hear stories about old code, sloppy code, code layered with many changes from many hands.
Another reason for a bridge: most products have some bits that have been around forever and generally just work. These could be perfectly usable. A different, older look and feel might speak “incompatible with the new stuff.” Deeply updating the code won’t benefit customer acquisition or retention, but a little css touchup keeps them from loking their age.