Good points. First being the placating of casual fans by doing something / anything. Yeah, most casual fans are like low information voters - ignorant of the big picture and facts, needing instant gratification.
Second, Suarez is about the only real impact power upgrade at 3B. But as other big market contenders are likely also in the hunt for such.... he's probably going to quickly travel outside of MIL's reasonable budget boundaries. Durbin has been good enough for what this team probably, really is this year (which is, still a 2nd tier team with too many needs than they can afford to fix via trades). Still, inquiring on the asking price for Suarez would be prudent. Just don't sacrifice too much prospect capital for a band aid rental.
Third.. and this is a kick in the marbles... yes, MIL has a surplus of MLB quality SP, but probably no meaningful way to leverage it to address their current needs. Usually, teams that are contending don't have this surplus to trade with. More typically, teams with quality pitching, and not in the race are selling starting pitching to bolster their farm with prospects. Their buyers are typically contenders. The Brewers don't need prospects for the future, they need a couple of thumper bats NOW. Very few impactful bat options exist, and most are on teams that won't trade from their big league roster as you mentioned.
Now that I type that last bit, the more I lean towards being OK with a packaged deal for a few months of Suarez IF MIL decides to go for it. Henderson, Black or Mitchell and Luis Pena? Just spit balling of course...
If prospects are all they can acquire for surplus pitching, I'd vote for some OF prospects who project to 15+HR type power.