As a systems developer myself, I’d say this is a lie. Given the complexity of the game in terms of all the other graphic animations, collision detections and calculations, I’d say the programmers have demonstrated to be extremely capable and skilled. In any craft in life, if you see a skilled persons work, you expect him to be able to do a “simple” task within his area of expertise. Refusal to do do can’t be because it’s not possible. If the real reason is “basically we don’t want to speed him up”, then just say so instead 
I fully agree with the OP, that this game needs more in app purchase options, which doesn’t turn it into a pay to win game. Back when the app market was new, this was a challenge for any game, but today, most of the do’s and don’ts have been learned, so it’s not that tricky anymore. Guidelines are:
- Let any significant buyable gamechanging effects/rewards also be available to the free riders through hard work. Reveal map is an example. Anyone can pay the 5K gold, or you can buy the permanent map reveal for real money.
- Let non-game changing effects/rewards only be buyable. The vanity items are an example.
Ideas for in app purchases in line with existing ones could be:
(a) Reveal shrines. You can pay 5K gold for the 1-2 shrines to be highligted on the minimap with a star/triangle or you can buy a permanent reveal shrine for real money. Given the hunter rings direct path to speeding up eternal item farming, particularly for new players looking for an expansion option, I could see this in app purchase being in demand.
(b) Reveal enslaver. You can pay 5K gold for an enslaver to be highligted on the minimap with a circle or you can buy a permanent reveal enslaver for real money. You never know if an enslaver is on the map, so there is a bit of a gamble involved. Given that you need to kill 200 enslavers to spawn a random legend pet, and not every map spawns an enslaver anyway, I’d say you’re still only getting a smaller advantage to find those legend pets.
(c) Maybe make a pack of all 3 map expansions, so you can buy both reveal map, shrine and enslaver with just one purchase of 15K gold, so the free riders don’t have too much clicking around to do just to get a map setup for a run.
Given that the cartographer/map guardian/portal is already displayed on the minimap, I would expect the code to be a simple task to improve to also show shrines and enslavers. Hence a good business case in terms of expected future revenue compared to development costs. If you were to make these options available, I’d expect them to be bought by anyone who has already payed for the permanent map reveal and who are still playing the game. As such, you should be able to determine expected revenue from a bit of analysis of your previous income from permanent map reveal.
Pets have massive room for improvement and could easily be enhanced with both gold-buyable enhancement for the free riders and permanent buyable enhancements for players who want to spend real money.
The “pet biscuit” suggestion is doable. You could buy a pet biscuit per map for 5K gold, which gives your pet an extra trick for this map or you could buy a permanent “pet collar” item for real money, which gives your pet a new trick. Only one collar can be equipped at a time so you can have more than one and switch them around depending on what trick you want the pet to have available. Maybe have 200 enslaver kills also drop a random pet collar.
There are tons of potential tricks to think of. Mainly, I think the current pets need balancing, as the fairy has a combat ability while the dog and imp only have a passive ability. They should all have a combat ability or a passive ability (or maybe have both a combat and a passive one). E.g. the frozen slowing of movement is so annoying on the ice maps when you don’t have “cannot be frozen” affix. The imp could be enhanced to have a combat skill “warm you up” (imps are hellish beings, right?) which removes frozen debuff and gets cast as often as the fairys wish. The dog could have a “bark” combat skill which stuns or fears monsters within a short radius of the dog and he barks as often as the fairy wishes. The fairy could have a passive “pick up mana/health orbs” skill as that would be in line with the wish combat skill and she picks up as often as the dog picks up gold.
