Lightweight block ciphers are mostly expressed for encryption routine and efforts are made to keep it as light as possible mostly in terms of gates count and power usage although some try to keep latency and critical path in consideration. The designers assume that such lightweight block ciphers will be used in a mode of operation which does not need the decryption routine like Counter mode. However, a few innovative designs also support the decryption routine with minimal overhead in terms of gate count like PRINCE and Piccolo block cipher.
Piccolo needs just 60 extra gates to support decryption on top of encryption circuitry.
Why is there a need for a lightweight block cipher to support decryption routine?
What all other lightweight block ciphers support decryption with minimal overhead in terms of gate count?
I know feistel structures do support decryption by using round keys in reverse order, but we are talking here about lightweight block ciphers. These are implemented in resource constrained devices and really small implementations of these lightweight block ciphers often cant afford to store expanded keys so even feistel structures do need extra gates to manage these issues for supporting decyption.
I do know modes other than Counter like CBC needs implementation of decryption methods, but what practical scenarios force this to happen. Cant the implementers just use counter mode.