I'm exploring the MTLS'es and found that I cannot set any other type of points in Float Remap than "Linear" (see the attachment) - is this some feature in particular use cases, or it is a temporary bug of this tool?
It's not a bug, there is a different node for a cubic ramp. Keep in mind these node are for creating mtlx compliant shaders and are limited by the spec. For a karma-specific houdini ramp, use a Karma Ramp Const node.