A disputed free-kick after 27 minutes saw Plymouth take the lead. Robbie Williams' 30-yard effort crashed against a post and bounced nicely for winger Onismor Bhasera to finish off.
Accrington finally found a way past Argyle goalkeeper Rene Gilmartin after 50 minutes when a high ball into the box was not cleared by the Pilgrims defence and it fell into James Beattie's path. The former England man walloped a low shot into the net from 12 yards out.
Richardson said: "We are disappointed we haven't won. There is always pressure to win your home games and we felt like we did enough overall to win based on chances.
"You do need the rub of the green sometimes and I am sure it will come."
Accrington keeper Paul Rachubka turned from hero to villain in the 1-1 draw.
Rachubka, on loan from Leeds, kept out Warren Feeney's penalty with just 12 minutes left after Michael Liddle was adjudged to have brought down substitute Paris Cowan-Hall. But he was then sent off in injury time after reacting when Feeney followed up a loose ball and challenged him.
Richardson added: "Their keeper pulled off three or four saves that he probably won't do again. He did fantastic and fair play to him but I think it was only right that our keeper saved the penalty. I didn't see the sending off but have spoke to Chub and will watch the DVD before I say anything about it."
Plymouth boss Carl Fletcher was happy with a point despite the penalty save.
"We haven't played great but we have dug in and so we are delighted with a point," said Fletcher. "We did not do some of the basics right but to have an off-day and get a point away from home on a wet, windy, slidey pitch makes it a good point for us."
- Sports & Recreation