A more correct way to describe obfs4 is "makes Tor traffic look like unidentifiable traffic", which is in itself potentially a suspicious marker for people who

A more correct way to describe obfs4 is "makes Tor traffic look like unidentifiable traffic", which is in itself potentially a suspicious marker for people who want to watch Tor users. If Tor makes up the bulk of identifiable traffic, the value add of being unidentifiable is not very high. This is an active area of research for the Tor project. Pluggable transports are not perfect and can be profiled by a determined adversary, although it takes more resources and sophistication than identifying unbridged Tor traffic.