JVM suffers from slow startup times and tends to eat a lot of RAM, even when the app doesn't technically need it around. It has an object model that spawns a bazillion tiny objects, and much of the JVM's GC design exists to cancel out those tiny object allocations.

JVM has many upsides (the portability and pluggable nature of JAR files is a huge one), but I think a lot of people are attracted to Go's bare-bones approach. Closer to the metal, a "better C", smaller overhead.