in a talent starved league like the nba more teams need to trade for low picks because their former top ones didn't work out
clearly another player like Irving won't help anymore than the likes of Kenneth Faried, Nolan Smith & Iman Shumpert
Clearly high lotto picks are the only way to get talent (eyeroll) lets just ignore that 7/15 all NBA players this year were drafted 15th or later or that 8/10 All Defense players were drafted 15 or later with Chris Paul (one of 2 top 3 picks) being a questionable decision.
A rebuild isn't possible with lotto picks, you need the college seniors and raw underperforming freshman in the early 20s. Also you need a power forward that can't get playing time on a playoff team.
Ultimately unless you are a good drafting team you need as many chances as you can get to try and get a good player. Besides Cleveland will have their own pick deep in the lotto from which to try and get a star or 2 so if they draft well (unlikey but this question exists about the brooklyn pick too) then they are set in 3 years to start the climb back to relevance. With 1 or 2 stars.
Monroe is just a useful backup big with a large expiring contract that there will be no presure to pay next summer. Nothing more. Perhaps a good trade asset to go after Boogie at the deadlie if New Orleans is looking to trade him.
Ultimately volume of picks and having Milwaukee's unprotected pick in 5 years time is nice. It leads to one of 2 scenarios
1. Kyrie + Milwaukee works out, the Bucks win multiple championships and Dan Gilbert gets to screw over Lebron and The Warriors. The picks are largely worthless but thats OK because Lebron gets no more rings.
2. Kyrie leaves Milwaukee as soon as Humanly possible and Milwaukee is now stuck with a hugely expensive roster (Parker needs to get paid soon) and a flawed depth chart. Milwaukee falls apart and those picks become worth a nice return.
Either of those scenarios should work nicely for Cleveland.