Capsules are heavy, but necessary.
Or at least, they are necessary for launch, landing, and stays in space lasting more than an hour or two.
But it is possible to imagine situations where cosmonauts would want to move quickly from one location to another, with a high relative velocity, where both the origin and the destinations have shelters. An example would be boarding an interplanetary cycler as it flies by.
For a "taxi" spacecraft, mass could be saved by eliminating the crew capsule. "The crew dresses up in EVA suits and grabs on to the rocker".
Understandably, no mission profiles to date have been suitable for such spacecraft. Almost all manned traffic is up and down to LEO, which requires a capsule. The exception would be Apollo, but there were no shelter infrastructure for it to take advantage of, instead minimizing risk by flying everything in a single stack.
The Lunar Escape System was such a capsule-free proposal, but it was only considered for emergency use.
Has such a capsule-free spacecraft ever been seriously proposed for regular use?