Is this just your personal oberservation? Or do you have stats showing this?
Here's the informal list (the ones that were pick for picks) from my time since first watching the draft in 1995. The analytics guy on Friedman's podcast more or less said he went through this exercise and decided he liked the names for the teams trading down which I would disagree with.
Once in awhile you'll get that home run like Anaheim got in 2011, but that's a little more rare than we like to think as armchair scouts. Usually the overriding thought it just how hard it is to hit on picks out of the top 20. Dallas' had a run of trading down in the late 90s / early 00s which turned out some really good players for the teams trading with them. Above average NHLers in bold (admittedly some debatable).
1996:
San Jose: #21 (Marco Sturm)
Chicago: #31 (Remi Royer) and #46 (Geoff Peters)
1997:
San Jose: #23 (Scott Hannan)
Carolina: #28 (Brad DeFauw) and
1998 3rd (Erik Cole)
1998:
Chicago: #8 (Mark Bell) and #94 (Matthias Trattnig)
Toronto: #10 (Nik Antropov), #69 (Jamie Hodson), #126 (Morgan Warren)
New Jersey: #27 (Scott Gomez)
Dallas: #39 (John Erskine) and #57 (Tyler Bouck)
1999:
NY Islanders: #28 (Kristian Kudroc)
Dallas: #32 (Michael Ryan) and #96 (Matthias Tjarnqvist)
2001:
Phoenix: #11 (Fredrik Sjostrom)
Calgary: #14 (Chuck Kobasaw) and #41 (Andrei Taratukhin)
Ottawa: #23 (Tim Gleason)
Philadelphia: #27 (Jeff Woywitka), #225 (David Printz), 2002 2nd (Tobias Stephan)
Florida: #24 (Lukas Krajicek)
New Jersey: #44 (Igor Pohanka) and #48 (Thomas Pihlman)
2002:
Washington: #13 (Alexander Semin)
Dallas: #26 (Martin Vagner), #42 (Marius Holtet), #185 (Francis Wathier)
Atlanta: #30 (Jim Slater)
Detroit: #41 (Joakim Lindstrom) and #96 (Jeff Genovy)
2003:
San Jose: #16 (Steve Bernier)
Boston: #21 (Mark Stuart), #66 (Masi Marjamaki), #107 (Byron Bitz)
New Jersey: #17 (Zach Parise)
Edmonton: #22 (Marc-Antoine Pouliot) and #68 (J.F. Jacques)
Florida: #25 (Anthony Stewart)
Tampa Bay: #34 (Mike Egener), #41 (Matt Smaby), #192 (Doug O'Brien)
Anaheim: #28 (Corey Perry)
Dallas: #36 (Vojtech Polak) and #54 (B.J. Crombeen)
2004:
Carolina: #4 (Andrew Ladd)
Columbus: #8 (Alex Picard) and #59 (Kyle Wharton)
NY Rangers: #19 (Lauri Korpikoski) and #247 (Jonathan Paiement)
Calgary: #24 (Kris Chucko) and #46 (Adam Pineault* pick later traded)
New Jersey: #20 (Travis Zajac)
Dallas: #22 (...) and #88 (Clayton Barthel)
San Jose: #22 (Lukas Kaspar) and #153 (Steve Zalewski)
Dallas: #28 (Mark Fistric), #52 (Raymond Sawada), #91 (Alex Edler* pick later traded)
2005:
San Jose: #8 (Devin Setoguchi)
Atlanta: #12 (...), #49 (Chad Denny), #207 (Myles Stoesz)
NY Rangers: #12 (Marc Staal)
Atlanta: #16 (Alex Bourret) and
#41 (Ondrej Pavelec)
Florida: #20 (Kenndal McArdle)
Philadelphia: #29 (Steve Downie) and 2006 2nd (Cory Emmerton* pick later traded)
Washington: #27 (Joe Finley)
Colorado: #47 (Tom Fritsche) and #52 (Chris Durand)
2006:
San Jose: #16 (Ty Wishart)
Montreal: #20 (David Fischer) and #53 (Mathieu Carle)
St. Louis: #25 (Patrik Berglund)
New Jersey: #30 (Matt Corrente) and #77 (Vladimir Zharkov)
Phoenix: #29 (Chris Summers)
Detroit #41 (Cory Emmerton) and #47 (Shawn Matthias)
2007:
San Jose: #9 (Logan Couture)
St. Louis: #13 (Lars Eller), #44 (Aaron Palushaj), aand #87 (Ian Schultz)
Minnesota: #16 (Colton Gillies)
Anaheim: #19 (Logan MacMillan) and #42 (Eric Tangradi)
St. Louis: #18 (Ian Cole)
Calgary: #24 (Mikael Backlund) and #70 (John Negrin)
Edmonton: #21 (Riley Nash)
Phoenix: #30 (Nick Ross) and #36 (Joel Gistedt)
2008:
Toronto: #5 (Luke Schenn)
NY Islanders: #7 (...), #68 (Shawn Lalonde* pick later traded), 2009 2nd (Mat Clark* pick later traded)
Nashville: #7 (Colin Wilson)
NY Islanders: #9 (Josh Bailey) and #40 (Aaron Ness)
Los Angeles #12 (...)
Anaheim: #17 (Jake Gardiner) and #28 (...)
Buffalo: #12 (Tyler Myers)
Los Angeles: #13 (Colten Teubert) and future 3rd (Ryan Howse)
Ottawa: #15 (Erik Karlsson)
Nashville: #18 (Chet Pickard) and future 3rd (Taylor Beck)
Washington: #21 (Anton Gustafsson)
New Jersey: #23 (...) and #54 (Patrice Cormier)
Minnesota: #23 (Tyler Cuma)
New Jersey: #24 (Mattias Tedenby) and future 3rd (Alexander Urbom)
Phoenix: #28 (Viktor Tikhonov)
Anaheim: #35 (Nic Deschamps) and #39 (Eric O'Dell)
2009:
NY Islanders: #12 (Calvin de Haan)
Minnesota: #16 (Nick Leddy), #77 (Matt Hackett),
#181 (Erik Haula)
Calgary: #20 (Tim Erixon)
New Jersey: #23 (Jacob Josefson) and #84 (Nic Deslauriers* pick traded)
Columbus: #21 (John Moore)
Anaheim: #26 (Kyle Palmieri) and #37 (Mat Clark)
Tampa Bay: #29 (Carter Ashton)
Detroit: #32 (Landon Ferraro) and #75 (Andrej Nestrasil)
2010:
Los Angeles: #15 (Derek Forbort)
Florida: #19 (Nick Bjugstad) and #59 (Jason Zucker* pick traded)
Montreal: #22 (Jarred Tinordi) and #113 (Mark MacMillan)
Phoenix: #27 (Mark Visentin) and #57 (Oscar Lindberg)
NY Islanders: #30 (Brock Nelson)
Chicago: #35 (Ludvig Rensfeldt) and #58 (Kent Simpson)
2011:
Toronto: #22 (Tyler Biggs)
Anaheim: #30 (Rickard Rakell) and
#39 (John Gibson)
Ottawa: #24 (Matt Puempel)
Detroit: #35 (Tomas Jurco) and #48 (Xavier Ouellet)
2012:
Buffalo: #14 (Zemgus Girgensons)
Calgary: #21 (Mark Jankowski) and #42 (Patrick Sieloff)
2013:
San Jose: #18 (Mirco Mueller)
Detroit: #20 (Anthony Mantha) and
#58 (Tyler Bertuzzi)
2014:
Chicago: #20 (Nick Schmaltz) and #179 (Ivan Nalimov)
San Jose: #27 (Nikolay Goldobin) and #62 (Justin Kirkland* pick traded)
NY Islanders: #28 (Joshua Ho-Sang)
Tampa Bay: #35 (Dominik Masin) and #57 (Johnathan MacLeod)
2015:
Philadelphia: #24 (Travis Konecny)
Toronto: #29 (...) and #61 (Jeremy Bracco)
NY Islanders: #28 (Anthony Beauvillier)
Tampa Bay: #33 (Mitchell Stephens) and
#72 (Anthony Cirelli)
Columbus: #29 (Gabriel Carlsson)
Toronto: #34 (Travis Dermott) and #68 (Martins Dzierkals)