I've been riding out at the Oaks for a long time as well, yes it is much different.
The key thing to remember is that the new trails are sustainable; they will not suffer the erosion from the rain we receive each winter. The new trails will not require the same amount level of maintenance each year.
All of the new trails held up exceptionally well during the heavy rain that we had earlier this year, they needed only very minor repairs. Other local parks required many hours of trail work before re-opening.
Did any of you ride Coachwhip (Mr. Wiggly) after the rains earlier this year? It had turned into a nearly continuous rut; as a consequence new lines were formed, making it even wider.
Many of the old, historic trails were point A to B routes, placed right on the fall line, a sure recipe for problems in the future.
The new trails may seem wide, but the brush will fill in, making the trails narrower, to the singletrack that I like. Just go and see how Deer Trail has filled in the past year.
If you don't like what is happening at Santiago Oaks, get involved. There any many opportunities to do so, either thru a mountain bike club or the OC Parks volunteer program.