I prefer black after 1. d4 Nf6 2. c4 e6 3. g3 c5 4. d5. Maybe 4. Nf3 to keep the opening within the strategic opening repertoire idea.

Well, some 20 years ago people tended to be more dogmatic than today, especially at club level. One line of reasoning was, with vintage wording :
- 1. d4 Nf6 2. c4 e6 3. g3 c5! is a bad benoni for White (better 3. Nf3 c5 4. d5!, since the gambit with ...cxd4 and ...e5 is unclear) ;
- 1. d4 Nf6 2. c4 e5 ?! is clearly dubious but spoils White's legitimate attemps to play it clean ;
- 1. c4 avoids the QGA, and 1...Nf6 is nothing because of 2. Nc3 e6 3. e4, but why allow the pesky 1...e5 ?
- hence 1. Nf3 followed by 2. c4 is appropriate, especially since 1. Nf3 Nc6?! (intending 2. c4 e5) is punished by 2. d4! when Black has to enter the infamous chigorin after 2...d5 and suffer for his foolishness after e.g. 3. g3 or 3. Bf4
- also after 1. Nf3 d5 (the correct move), White can play the principled 2. c4 with full compensation after 2..dxc4, while 2...d4 simply drops a pawn for some temporary activity. Or if White prefers, he can just go 2. b3 keeping all options open.
- against the Dutch, 1. c4 is excellent since you can fight later for e4, but whatever your move order you can wait for Black's weak squares to reveal in the middlegame ; etc...

Nowadays, if you want to play in strategic fashion with d4, c4 & g3, you may need to have something ready against non-cooperative attemps such as:
- the early ...c5 which still looks good for Black ;
- the Budapest ;
- the Chigorin, Albin, QGA and slave-like systems.

Maybe the Benoni and Budapest are the most challenging to your move order ?