The 34-year-old midfielder received the punishment on Wednesday after admitting a Football Association charge.
Barton, who placed 1,260 bets on matches between 26 March 2006 and 13 May 2016, has admitted he is addicted to gambling.
“Eighteen months seems a long time to me in light of other things I’ve seen in the sport,” said Dyche.
Barton plans to appeal against the length of the suspension, calling it “excessive”.
- ‘I’m addicted to gambling’ – Barton’s statement in full
- Flawed & controversial – the complex career of Joey Barton
- Gambling companies prey on ‘vulnerable’ footballers
- 53 footballers reported over potential breaches of betting rule
Dyche confirmed Barton, who re-joined Burnley from Rangers on a short-term deal in January, will not be offered a new contract in the summer.
The ex-England international was in his second spell at Turf Moor before the ban, having helped the Clarets reach the Premier League in the 2015-16 season.
“We thought there was a chance, of course [of this happening],” added Dyche. “We’re not naive. Joey understood that. On the football side of things we didn’t want it to get in the way of thinking he was a worthwhile player to bring back. We wanted to get on with it, give him a platform and he’s done that.”
- ^ 18-month ban (www.bbc.co.uk)
- ^ a nine-month ban (news.bbc.co.uk)
- ^ ‘I’m addicted to gambling’ – Barton’s statement in full (www.bbc.co.uk)
- ^ Flawed & controversial – the complex career of Joey Barton (www.bbc.co.uk)
- ^ Gambling companies prey on ‘vulnerable’ footballers (www.bbc.co.uk)
- ^ 53 footballers reported over potential breaches of betting rule (www.bbc.co.uk)