Natural being better than synthetic is a fallacious argument.
There are thousands of natural compounds that are poisonous and bad for you, (strychnine, curare, etc). Even natural substances that are very poisonous and shamans use(tropanes from datura/brugmansia plants, etc)
At the same time many people have had life changing experiences with synthetic substances (me included, when I first dosed LSD). South african shamans prefered 2CB over their traditional plants :
http://www.evolver.net/user/chen_ch..._traditional_entheogens_south_african_healers
Also, you dont know whether a substance that is made synthetically isnt found naturally in plants. Take the example of DMT, it was first synthesized in a laboratory, and only later it was found to be in plants. Who knows, maybe LSD is being made in some plant
You can speak for yourself of course, and say that YOU preffer natural substances X,Y and Z over synthetic substances P, Q and R, but to base your whole judgement in whether a substance is (as far as you know) only man-made or if its found naturally, is a poor argument IMO. Specially to judge it for others, saying something is 'bad' or 'good' in absolute terms is out of place imo.
Having said this, personally the substances I use the most and have gained most out of are, coincidentally or not, naturaly found (ayahuasca/dmt/beta-carbolines, cactus/mescaline, mushrooms/psilocin). BUT, I have also had my life changed because of LSD, and definitely preffer it to LSA-containing seeds.
I think one of the big problems with many synthetic drugs is related to their source (often coming from unscrupulous sellers and middle men, being made in chinese labs with little quality control, etc), to their purity, and to the possibility of mislabelling (if you consume a large 2CB dosage but if they made a mistake and sold you some bromodragonfly, you might die, as it happened with the owner of a research chemical company a couple of years back. Think about it, if even the owner of a company can die from such mistakes, the end users are even more at risk). Because of that, we in the nexus always suggest people have their substances tested if they have a testing organization in their country, or that they test it themselves at least with simple reagent tests which are inexpensive and unwatched, or with a bit more advanced TLC which can also be made at home if one studies a little bit how its done. All the info is in the subforum linked in my signature.