With the cancellation of the second iteration
of the TV network series "Roseanne," now, in 2018,
veterans of both shows are waxing eulogic.

As stated in the OP,
Glenn Quinn didn't live to see the second version of "Roseanne."
What the OP leaves out is Glenn Quinn's casting
in the original "Roseanne."
He played Becky's boyfriend.

Glenn Quinn      1970 - 2002

as you can see, he died tragically young.
He overdosed on heroin.
By the grace of God and one trustworthy friend,
he did not die on the streets, though he could have done.

The account in the news reads that
Quinn showed up at a friend's apartment (Los Angeles)
and asked to spend the night.
Next morning the friend had a job to report to.
He glanced at Quinn, motionless on the couch in the next room.
Judging him asleep (there had been no health red-flags otherwise)
the friend stepped out and left Quinn in peace.

It came, one presumes, as an unspeakable surprise
when the tenant returned, saw the motionless Quinn,
and, touching him, realized that Quinn had died there.

Glenn Quinn was one of several progeny of
a tumultuous marriage.
The first-born child of the couple
showed up "on the wrong side of the blanket,"
before the young parents were wed.
This oldest son was put up for adoption.
Glenn was the youngest of the children
who were born to the couple once they were wed.

"Murty" Quinn, the father, was a musician of some reputation in Ireland.
When the marriage came apart,
the ex-wife, Bernadette, Glenn's mother,
headed to Southern California
where there were already close relatives in residence.

Glenn Quinn got into the business from the bottom and climbed his way up.
His good looks and irrepressible personality took him far.

Ciaran, Quinn's big brother who had been put up for adoption,
never knew Glenn Quinn.
As an adult he looked up his birth relatives,
and discovered Glenn Quinn's life, career, and pathetic demise.
Today, Ciaran has Glenn Quinn's drum set,
courtesy of the bereaved birth-mother, Bernadette.