Problem with the way rested bonus is setup in this game

If you accumulate an entire day or so worth of rested, that's all fine and dandy if you end up using it on your higher level character. The problem is, if you make the mistake of starting to work on a lvl 1 trade skill, the rested will be used up almost immediately (in either 1 or only a few things you create). Banked rested exp should not be a % bank, it should be a number bank, the percentage aspect should just be used to add a bonus amount on top of what your normal exp would be. What I mean is, the system i'm talking about works like this (and it's used in various other games, I didn't come up with it), if you log out for a night in an inn you gain for example maybe 5000 EXP (just an example number) of rested bonus in that time frame, every time you do an action, you gain normal exp + 100% rested bonus, so let's say for example you do something that grants 1000 normal exp, + 100% rested bonus = 1100 exp, that number then is subtracted from the 5000 exp of rested you accumulated. This will make it so that low level trade skills aren't eating up your rested bonus almost instantly.

I haven't seen this. Leveled on my lower level class with rested and it lasted as would be expected. Might not have been paying attention though.

I had a half a bar on my lvl 23 lancer, went to start leveling my lvl 1 weaver, made about 3 bolts of the lvl 1 cloth and my rested bonus was gone. It was quite silly really.

I could maybe understand not wanting to have people bank a lot of rested exp to be used on lower level crafting and such, but in that case just make the rested exp job independent. What I mean is in order to get rested for your weaver you have to log out inside an inn on your weaver.

I had the same problem. If I just hit 50 archer and wanted to go to my craft, and wasn't able to use my rested as a result of them 'fixing' this issue, I would be a little upset. It just takes some awareness. I doubt people will make the mistake twice.

In regards to your integer vs percent argument, I disagree wholeheartedly. This would make you generate the same at level 1 as level 50, either weighting the amount you get later heavily, or giving you an endless surplus of rested until mid range levels. The only way to provide an calculated boost without having mismatched XP at levels while including the ability to transfer you rested from one job or craft to another is to go by the percentages.

Other games you've played also give you a bonus given by a percent of your current XP bar. What separates this from the other games is that your crafting actually switches your lvl xp with your crafting xp, rendering crafts as a class with an XP Bar. As a test, log into world of warcraft on a level 1 and sit in an inn overnight. You'll accumulate maybe 4,000 xp. Now log out as a 89. You'll accumulate that much per second.

a bit confused at just whether there is an issue with the system, or an issue with how it is being compared.

You are comparing the slower xp rate of killing mobs versus the accelerated xp rate of crafting--not a fair comparison. Also, you are comparing how the rested bonus is showing in the TNL space of different XP bars for different jobs/levels, so it may be a little misleading visually as well.

For example, I logged out last night as an 18 CNJ, close to 19 (just need to finish one of the last 2 objectives on it's hunt list to ding 19). My rested XP was rolling over on that job, so it was the light blue bar. I changed to my 17 ALC, which had just dinged 17, and my rested xp was extended as a bronze bar to about 2/3 or so of the xp bar. I made 4 Ethers, and synthed 38 cloves into oils, and there was still a sliver of my rested xp left. Bear in mind, that I was getting upwards of 1100 xp PER SYNTH--when I got quality past 20%, it would sometimes hit 1800+.

Yes, I burned it down in a matter of minutes vs. closer to an hour smacking mobs....but I was burning it at 4 or 5 times the amount of return per event that rewarded XP. If you are getting 1000/synth it will take considerably fewer events to burn say... 20k of bonus xp versus doing it at 300/kill out in the field. Couple that with how long it takes to synth 20 items versus soloing 67 mobs capable of maintaining 300 xp/kill on average, and you can see that one will most likely take longer than the other.

[Edit:]
Note also that your bonus applies to xp earned just for your actions. It doesn't apply to rewards from FATES/quests, only from the xp you get from killing each mob. With crafting, that is all you are earning XP on (unless it's your first synth in the log or crafting for a quest and getting a reward there)--so you may well be seeing it burn down in a much more focused manner when crafting vs out in the field where you get small xp/kill rewards and big bonuses from content like hunt logs and FATES. For example... level 10 bombs out in the summer event FATE that yield like 50-70 xp/kill and then you get a few thousand XP when it ends. You can earn that much xp from just a few synths.