change vertex dissolve not to collapse edges when its only connected to 2, rather then joining the faces on either side.

This way. IMHO is more useful since it means you can simplify the geometry between faces without joining them and it distinguishes vertex dissolve more from edge dissolve - which will join both faces still.

source/blender/bmesh/operators/bmo_dissolve.c

@@ -334,7 +334,7 @@ void dissolveverts_exec(BMesh *bm, BMOperator *op)
 			if (BM_vert_edge_count(v) == 2) {
 
 				/* collapse the ver */
-				BM_vert_collapse_faces(bm, v->e, v, 1.0f, TRUE);
+				BM_vert_collapse_faces(bm, v->e, v, 1.0f, FALSE);
 				continue;
 			}
 

source/blender/bmesh/tools/BME_bevel.c

@@ -153,6 +153,9 @@ static int BME_Bevel_Dissolve_Disk(BMesh *bm, BMVert *v)
 
 		e = v->e;
 		elast = bmesh_disk_nextedge(e, v);
+
+		/* BMESH_TODO, figure out if its possible we had a double edge here and need to splice it,
+		 * last bool arg */
 		bmesh_jekv(bm, e, v, FALSE);
 
 		l1 = elast->l;