Answer:
Coaxial cable has a few disadvantages.
1) It tends to be more ridged and more difficult to bend around tight corners.
2) It has a tendency to pick up signals around it unless shielded. This is called the induction effect. Power transformers, high signal cables, home power lines can all cause interference on the cable.
3) Imperfect shielded can cause a grounded loop. You'll see this some times on older cable TV Boxes where you have a bar of slight distortion that just runs across the screen over and over again, perhaps slowly upward? Proper installation with good grounded will limit this.
4) For the most part 10base2 is about as fast as you'll ever get on a coaxial cable without special circumstances.
5) It's ancient and being phased out except for special use by cable companies and some telcoms.