Well lets see, in a whole day right the entire LTC and DOGE networks bring in a total of $1.58 million dollars combined from fees and inflation (fees being utterly insignificant).

Bitcoin, from *fees alone* without any inflation brings in $1.72million dollars/day.

This means that even with inflation completely gone in Bitcoin, Bitcoin already brings in enough in fees pay for significantly more security than those two altcoins achieve essentially entirely from inflation.  (You could, for whatever it's worth substitute or even add other semi-popular altcoins to that and still be less than Bitcoin, I just used the two you suggest)

"Merged mining" is significantly undermined by the central game theory argument for mining:  The game theory argument for mining is that to mine you expend costly energy, and if your work won't end up in the longest chain (or you manage to blow up the thing you're mining) then that effort is wasted so it is in your best interest to mine honestly.  It gets some participation advantage because you can just add it on, but as we saw with namecoin the low income quickly causes parties to either no bother or not maintain their infrastructure.

In the case of merge mining if one asset has meaningful income (like dogecoin maybe has with its perpetual inflation) and the other asset does not-- like litecoin once is subsidy is depleted (unless something changes). Then only the income side has meaningful security, the non-income side does not because the attacker isn't losing much if his blocks don't end up on the longest chain or if he sets the whole thing on fire.

Maybe you can see why many Bitcoiners really dislike altcoiners.  It's usually not that they have any issue with the altcoin itself, it's because people with some kind of investment in the altcoin glibly spread misleading claims about Bitcoin in order to rationalize, justify, and promote their altcoins.  The points are seldom well justified or considered.  I'd say that a simple majority of altcoin centric arguments about Bitcoin are actually points against the altcoins if considered with a bit of care, like this one.

There may well be reasons that you could advocate ltc+doge,  but fudding Bitcoin about its ability to fund security with fees is not one of them.  If Bitcoin's *current* fee-only income isn't enough security income for your taste than you should conclude that these other coins are *currently* insecure and lack any kind of trajectory to allow them to achieve even their current level of security in the future (after all, even doges perpetual inflation effectively dilutes the mining income down to nothing over time too; just at the cost of also debasing everyone's holdings at the same time).

Argues? Where? AFAICT noise, toxicity, and attacks got so bad the discussion just *stopped*, except a bit of chatter among gadflies and navel gazers that won't ever do the work and can't manage the navigate the public politics.  Maybe you've seen some arguments among  those people, but they were only ever there to argue.  Or it's just unoriginal repetition of ideas that were thoroughly explored in 2012 (like "lets switch to scrypt and merge mine with litecoin!"), getting the responses that could have been copy and pasted from the last three times. If there was real activity you probably wouldn't notice those noise discussions arguing amongst themselves.

When I looked recently the developer chat channel logs, they now regularly go days without any comments at all, yet back in 2013 they averaged 1866 messages per day-- a day without activity would have been a shock.  That isn't argument-- argument would mean activity.  The mailing lists have been widely unsubscribed, most posts are people who've never been extensively involved in development, and just haven't received the message about how dead things are in terms of meaningful change.

Of course, (reinvoking the prior offtopic diversion) bitcoin development "dead" is still significantly more activity than most altcoins get-- so altcoiners don't get any ideas from this comment.  Just about a year ago or so the entire doge network was completely unable to bring up a single new node for *weeks*  until a bitcoin developer friend had a friend that wanted to dump their doge (the outage actually drove up prices because it limited the supply of old coins).  He had to fix some gross incompetence that was preventing nodes from syncing  (such as completely re-validating the defectively expensive scrypt POW and the gigant MM proofs every time it read one off the disk to give it to a peer) then used his fixed node to fix the other nodes, and brought their essentially failed (but hardly noticed failure since pools and exchanges were still running) network back to life.  Maybe next time no family member of a real developer will have doge to dump and it will just stay dead?  who knows!