Index: trunk/src/org/openstreetmap/josm/data/osm/AbstractPrimitive.java
===================================================================
--- trunk/src/org/openstreetmap/josm/data/osm/AbstractPrimitive.java	(revision 18074)
+++ trunk/src/org/openstreetmap/josm/data/osm/AbstractPrimitive.java	(revision 18075)
@@ -23,5 +23,4 @@
 import java.util.stream.Stream;
 
-import org.openstreetmap.josm.data.gpx.GpxConstants;
 import org.openstreetmap.josm.spi.preferences.Config;
 import org.openstreetmap.josm.tools.Utils;
@@ -799,5 +798,5 @@
             List<String> l = new LinkedList<>(Arrays.asList(
                 "source", "source_ref", "source:", "comment",
-                "watch", "watch:", "description", "attribution", GpxConstants.GPX_PREFIX));
+                "watch", "watch:", "description", "attribution"));
             l.addAll(getDiscardableKeys());
             l.addAll(getWorkInProgressKeys());
Index: trunk/src/org/openstreetmap/josm/gui/layer/gpx/ConvertToDataLayerAction.java
===================================================================
--- trunk/src/org/openstreetmap/josm/gui/layer/gpx/ConvertToDataLayerAction.java	(revision 18074)
+++ trunk/src/org/openstreetmap/josm/gui/layer/gpx/ConvertToDataLayerAction.java	(revision 18075)
@@ -17,4 +17,6 @@
 
 import org.openstreetmap.josm.actions.SimplifyWayAction;
+import org.openstreetmap.josm.data.gpx.GpxConstants;
+import org.openstreetmap.josm.data.osm.AbstractPrimitive;
 import org.openstreetmap.josm.data.osm.DataSet;
 import org.openstreetmap.josm.data.osm.Way;
@@ -70,5 +72,11 @@
             double err = SimplifyWayAction.askSimplifyWays(ways, tr("Would you like to simplify the ways in the converted layer?"), true);
             if (err > 0) {
-                SimplifyWayAction.simplifyWays(ways, err);
+                try {
+                    // Consider the GPX tags uninteresting temporarily, to make sure it doesn't prevent simplification to remove nodes
+                    AbstractPrimitive.getUninterestingKeys().add(GpxConstants.GPX_PREFIX);
+                    SimplifyWayAction.simplifyWays(ways, err);
+                } finally {
+                    AbstractPrimitive.getUninterestingKeys().remove(GpxConstants.GPX_PREFIX);
+                }
             }
             final OsmDataLayer osmLayer = new OsmDataLayer(ds, tr("Converted from: {0}", layer.getName()), null);