Why is ArcGIS Online symbology customization so limited?

[chrisvincent112]

I work for city government and we need to make a lot of public-facing web maps. The symbology options in ArcGIS Online are so limited compared to ArcGIS Pro. For me, the major omissions are the lack of "layers"  for line symbology so you can create line borders and more complex dashed lines, and no hatched or pattern fill on polygons. The "gallery" option in Pro provides so many good templates for lines, but none of them are available in ArcGIS Online, from what I understand. I've tried to create custom line symbology by creating multiple copies of layers to create layered symbology, but then ArcGIS Online does not allow you to exclude items from the legend, so the legend gets garbled with all the copies. 

Can ESRI prioritize improving this functionality? 

[simoxu]

If cartography is critical to your application, can you use map image layer or tile layer?  these layers are pre-rendered in ArcGIS Pro or dynamically rendered on the server. 

Feature layers are rendered in the browser and as you observed, with simple symbols.

Please see the ArcGIS layers types below for more information:

Layers—ArcGIS Online Help | Documentation

[ShaneONeill_144]

If downgrading the symbology is not desired then another option is to create a tile service. When a tile service is created, tiles are created exactly as seen in ArcGIS Pro. To avoid credit usage for tile generation, users can build tiles for their map in ArcGIS Pro by creating a tile package (.tpk) first and then uploading the tile package to ArcGIS Online to publish as a tile service. For more information, refer the section entitled 'Build and publish a tile package' in the following ArcGIS document, ArcGIS Help: Publish tiles.