Sadly, SNMP is still in common usage. Later versions of the protocol have addressed numerous issues in SNMPv1, but those have almost entirely been directed at fixing the security model. As a result, SNMP traffic is now comparitively bloaty, but they have not addressed what I consider to be the glaring shortcoming in SNMP - that data stored in the MIB resides outside the monitoring/monitored device exchange.
The separation of the MIB-stored data from that exchange, and the consequent use of numeric OIDs on the wire, made sense in SNMPv1, as it kept most exchanges to a single UDP datagram in each direction. As of v3, it no longer makes any sense, to my mind - but I'm not the IETF.
Sadly, SNMP is still a sort of lowest-common-denominator management protocol, and I'm constantly surprised how many devices I see out there where the easiest way to extract monitoring data from them is good old RO-community-string-in-UDP-based SNMPv1.
Edit (2018): because it's so germane, I quote from Geoff Huston's excellent article in the August 2018 edition of the Internet Protocol Journal:
The Internet converged on using the Simple Network Management
Protocol (SNMP) a quarter of a century ago, and despite its security
weaknesses, its inefficiency, its incredibly irritating use of Abstract
Syntax Notation One (ASN.1), and its use in sustaining some forms
of Distributed Denial-of-Service (DDoS) attacks, it still enjoys widespread use.