ICMP or No ICMP

Lately, I've been looking a lot into ICMP packets. Most people only pay attention to TCP and UDP packets, while most just know that ICMP packets are used for pings, traceroutes and others. Well, I've been looking into various other uses for ICMP packets, but one question came to mind? Should ICMP packets be used for other purposes besides their original intent? Would the makers of the Internet get upset if people started using ICMP packets to communicate data, the same way that they use UDP packets, if so, why would anyone want to even consider that approach?