Why?
1)They have Swanson for that.
2)He can pitch multiple innings (unlike Ward)
3)The last I heard is that the long term plan is to still make him a starter.
I don't disagree with your assessment of not turning Pearson into a 1 inning specialty reliever.
As an asdie, Ward could certainly go multiple innings like most pitchers from the 80's and early 90's . Relievers (and starters for that matter) were not babied like today team could run through the season with 10 man pitching staff and extra innings with no real issues.
Most pitchers today are close to 1:1 ratio.
The amount of innings Ward pitched between 88 and 92 is generally unheard of today for a reliever, and he was nothing special in that regard.
Games / Innings
1988 - 64 Games, 111 Innings
1989 - 66 Games, 114 Innings
1990 - 73 / 127
1991 - 81/107
1992 - 79 / 101
The ratio got less and less by 1991 and 1992 - that is the start of the period where managers started to slow down the innings for relievers.