You're not seeing the problem because you missed the point. That one piece of content which is being stretched incredibly thin across 10+ months only exists because of a third party website/tool the dev team actively dislike. Think about that. It isn't the content itself having any sort of replayability on its own but a secondary source outside of the game giving it one. Now, of course, battle content is finite is every game. However, most games have enough to last a decent length of time relative to both the genre and expected longevity. FFXIV doesn't. And the alternative content it does offer has no longevity. Which brings us back to the other point you missed: people, myself included, want more to do than one or two things.
V/C Dungeons, Island Sanctuary and Relics are all content that had/has absolutely zero staying power this expansion either due to lackluster rewards, poor implementation or a combination of both. To answer your question, I'm not "upset" I reached some arbitrary goal I never made for myself, I'm disappointed every other piece of content has no longevity so that I have more alternative things to partake in than log farming.
I never said you couldn't like it. Just expect people are going to disagree with you, especially when your argument hinges entirely on "so I can play other games." Which, by the way, is a completely fine mindset to have. The problem arises when you're upset because other people want more reasons to play this game. In fact, to better illustrate this point, let's create a new relic step come 7.0
We'll go back to the Exploratory Zone and toss in all sorts of ways to progress the relic, some grindy, some not. Make it all a little more involved than Bozja but with some quirks like an actual hunting log or quests relating to that zone. We'll even toss in some bonuses on the relics ala Hydatos exclusive to the zones themselves to give players who want that little extra power something to achieve. We'll cap this off with a Baldesion/Delebrum type raid, albeit with a better queuing systems.
Now here's the caveat. Unlike the lackluster futureproofing both Eureka and Bozja have, we'll make it so you can purchase a replica of every step via tomes sometime during 8.x. In other words, we'll use the EW method for futureproofing.
Everyone gets what they want, right? You have all the time in the world to play different games, especially if you'd rather just wait until the replicas release while players who like the Exploratory Zones get to grind things out. Oh, you don't want to wait to tackle content and feel like in this hypothetical you'll have nothing to do during 7.0? Welcome to how the rest of us feel right now.
The problem people seemingly like to ignore when arguing how they prefer a simple method like tome farming so they can play other games or due to having twelve jobs and eighteen kids is those who want to play FFXIV have less content. You can simply choose not to do <insert content> like Bozja if it doesn't appeal. Or wait for the eventual nerfs to make progression faster. The rest of us don't have a choice this expansion. There just isn't anything else to do. If we opted out of the relic... well, we get even less despite wanting to play FFXIV.