RE: the quote from elsewhere about warlocks not needing to be low on Con and letting Hex drop and giving warlocks a third attack. There's so much context missing that I don't see what relevance that quote has to do with ranged attacks, so I will restrict myself to the first part of Ashrym's reply.
The warlock would lose an action to disengage/dash on a melee opponent by disengaging or dashing without expeditious retreat on an opponent that is within 5 ft or else be forced to attack with disadvantage for a penalty.
Longstrider and expeditious retreat isn't sustainable because longstrider is burning through 6 spell slots already at 2 per hour with 2 short rests and expeditious retreat is generally once per encounter while using concentration. Either ground or damage is also lost the first round in casting expeditious retreat because the bonus action is already gone for expeditious retreat so the action is used for dashing or attacking but not both. The initial range of 100 ft is also questionable because it depends on visibility that's impacted by nightfall, weather, terrain, and not typical in dungeons at almost any time. One of the issue with kiting we run into is there needs to be a place to run to and that's often problematic, hence my comment about dungeons versus open wilderness.
You've turned your wizard into a rather poor kiter at that level and that's all the warlock would be doing at that level.
First of all, on the round you cast Expeditious Retreat, you get the effect of a Dash, so there is no lost round in there.
Second, outside of dungeons (because I agree, range isn't a great defense in dungeons), 100' is an absurdly close range to begin an encounter at. That's why I said it favors the ogres. 200' to 2000' would be a more typical range. A city block is usually between 300' and 600' feet long (900' in Manhattan)--when was the last time you had trouble seeing someone standing at the other end of the block? The DMG gives standard outdoor encounter range as 2 miles, down to 1 mile in rain or 100' to 300' feet in fog. Unless you're on the Demiplane of Dread, constant fog isn't likely to be an issue in most settings. If it is foggy, just wait for the fog to evaporate before beginning your day. DMG also says visibility can be up to 40 miles from a mountain on a clear day; last night my PCs had an encounter at 500,000 miles, which looked like only 15 miles due to spelljamming effects. (They chose to bypass it instead of engaging, but they could have engaged if they'd wanted to.)
Third point: "Longstrider and expeditious retreat isn't sustainable" on a fifth-level party. You mean you can't keep it up 24 hours a day? I agree. If the ogres jump out of the trees when you're picking your way through the forest on your way to meet someone else entirely, Expeditious Retreat may come into play but probably not Longstrider; what's going to happen is that the paladin will activate (remember the guy who didn't do anything but is "insurance" for when range can't help?) and the ranged guys will support him while he melees. Note that longstrider is optional: if you start at 200' instead of 100', you can kill the ogres by sacrificing 80' of distance instead of 2 spell slots, which is a good deal in open terrain unless you're facing a whole ton of ogres. Longstrider is more something that you use in relatively close terrain when you have general intelligence on a threat, "theres's a fort full of orcs and ogres", or when you are already fleeing in panic from 15 ogres who just jumped your whole party from the bushes and the stupid paladin keeps falling behind and getting opportunity attacked.
One reason I prefer Mobile to Longstrider in the general case is precisely because keeping Longstrider up all the time is a real pain, plus Mobile lets you melee kite. Using Mobile, even the wizard could kill the ogres solo, with or without cantrips.