I agree fully. These coins are worth a lot more than the market price suggests. Enjoy it while it lasts. If all those people collecting things that exist by the millions all of a sudden started collecting ancients, I'd be left with a $50 bag full of key date cents only worth face value and that does not seem like much fun at all. Don't tell your friends.
I really wonder how much the last part of your statement plays into collector demand. I view coins as at least a quasi Veblen good, a commodity where demand increases proportionally with high prices. The high prices paid for the top specimens can often draw people into collecting either that series, or that coin in particular. But in order to get really high prices, I think you need more than just limited supply and high demand, I think you also need eye appeal. I think the low grade/eye appeal of so much of the republican bronze keeps the big money out of the series as I think it's hard for many high budget collectors to justify spending 5/6 figures on ugly and often small coin. And without at least a couple really nice examples of republican bronze fetching big money you don't get a Veblen good effect where the high price drives further demand.
Constantine died in 337, not 377, but that is unimportant as regards VRBS ROMA Centenionales. They were issued beginning in 330 alongside of the CONSTANTIOPOLIS city commemoratives as well as the very, very common GLORIA EXERCITVS - 2 soldiers and 2 (later, one) standard(s) between them - all part of the same huge emission of Centenionales in honor of Constantine moving the administrative capital from Rome to Constantinople. That is why there are 2 main types of city commemoratives - one to honor Rome, the other to honor Constantinople. The VRBS ROMA and CONSTANTINOPOLIS allegorical city representations survived as obverse types, often paired with Gloria Exercitus or Vota reverses up until the final emission of VICTORIAE DD AVGG Q NN) 2 Victories centenionales and accompanying Votas, which were the final issue of Centenionales in the Constantinian-era, just before the reforms which introduced the larger Majorina coins which are typically mainly associated with FEL TEMP REPARATIO (several types, at first, later just the soldier and unfortunate horseman that is so common) reverses.
I have always been amazed at the demand patterns for Republican coins. Even here on CT, we regularly see posts of denarii very much based on the coin being high grade or even 'best known'. Denarii are widely varied with wonderfully historic designs but we see relatively few people proud of their extreme rarity unless it is also attractive. Republican AE is the opposite. The vast majority have a somewhat boring prow reverse and rarities are distinguished by things like a couple letters or (eg crescent shape) minor device. People are thrilled to show an as with one face missing or a minor type that is 90% worn off as long as it is a 'good one'. We rarely see people posting uncirculated commons (may not exist???) but even coins well struck with good surfaces are the exception rather than the rule. My daughter is a school teacher. Her licence from the state allows her to teach kindergarten through eighth grade. I have known many teachers and truly believe the persons fully comfortable teaching both ends of that range are extremely scarce if they exist. I see Republican collectors in a similar manner. The personality/skill set need to collect both AR and AE are as unusual to be combined in one person as is the teacher really good with teens and toddlers. I have a few RR bronzes but have absolutely no interest in gathering a set of rarities in the grade we usually see offered. Similarly, I am not willing to chase silvers in EF+ when I already have one in VF. As a Republican collector, I am no good on either end. We have a few people here on CT reasonably skilled where I am not.